As filed with the Securities and Exchange Commission on December 3, 2018

Registration No. 333-227884

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

Amendment No. 1
to
Form S-4
REGISTRATION STATEMENT
UNDER
THE SECURITIES ACT OF 1933

SCIENCE APPLICATIONS INTERNATIONAL CORPORATION
(Exact name of registrant as specified in its charter)

12010 Sunset Hills Road, Reston, VA 20190
(703) 676-4300

(Name, address, including zip code, and telephone number, including area code, of registrant’s principal executive offices)

Charles A. Mathis
Executive Vice President & Chief Financial Officer
12010 Sunset Hills Road
Reston, VA 20190
(703) 676-4300

(Name, address, including zip code, and telephone number, including area code, of agents for service)

Copies to:

Approximate date of commencement of the proposed sale of the securities to the public:

As soon as practicable after this registration statement becomes effective and upon completion of the transaction described in the enclosed document.

If the securities being registered on this Form are being offered in connection with the formation of a holding company and there is compliance with General Instruction G, check the following box.    o

If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.    o

If this Form is a post-effective amendment filed pursuant to Rule 462(d) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.    o

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act:

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act.    o

If applicable, place an X in the box to designate the appropriate rule provision relied upon in conducting this transaction:

Exchange Act Rule 13e-4(i) (Cross-Border Issuer Tender Offer)    o

Exchange Act Rule 14d-1(d) (Cross-Border Third-Party Tender Offer)    o

The Registrant hereby amends this Registration Statement on such date or dates as may be necessary to delay its effective date until the Registrant shall file a further amendment which specifically states that this Registration Statement shall thereafter become effective in accordance with Section 8(a) of the Securities Act of 1933, as amended, or until this Registration Statement shall become effective on such date as the Securities and Exchange Commission, acting pursuant to Section 8(a), may determine.

PRELIMINARY—SUBJECT TO COMPLETION—DATED DECEMBER 3, 2018
MERGER PROPOSED—YOUR VOTE IS VERY IMPORTANT

The board of directors of Science Applications International Corporation (which we refer to as SAIC) and the board of directors of Engility Holdings, Inc. (which we refer to as Engility) have agreed to an acquisition of Engility by SAIC, under the terms of the Agreement and Plan of Merger, dated as of September 9, 2018.

If the transaction is completed, Engility stockholders will have the right to receive 0.450 of a share of SAIC common stock for each share of Engility common stock they own at closing (which we refer to as the exchange ratio), with cash paid in lieu of fractional shares. The exchange ratio is fixed and will not be adjusted to reflect stock price changes prior to closing of the merger. Based on the closing price of SAIC common stock on the New York Stock Exchange of $89.86 on September 7, 2018 the last trading day before public announcement of the transaction, the merger consideration represented approximately $40.44 of aggregate value for each share of Engility common stock. Based on the SAIC closing price of $69.52 on November 29, 2018, the latest practicable date before the date of this document, the merger consideration represented approximately $31.28 of aggregate value for each share of Engility common stock. SAIC stockholders will continue to own their existing shares of SAIC common stock. We encourage you to obtain current market quotations of SAIC common stock and Engility common stock before voting.

Upon completion of the merger, we estimate that current SAIC stockholders will own approximately 72% of the combined company and former Engility stockholders will own approximately 28% of the combined company. SAIC common stock and Engility common stock are both traded on the NYSE under the symbols “SAIC” and “EGL”, respectively.

At the special meeting of SAIC stockholders scheduled for January 11, 2019, SAIC stockholders will be asked to vote on (i) a proposal to approve the issuance of shares of SAIC common stock to Engility stockholders, which is necessary to complete the merger, and (ii) a proposal to approve the adjournment from time to time of the SAIC special meeting if necessary to solicit additional proxies if there are not sufficient votes at the time of the SAIC special meeting, or any adjournment or postponement thereof, to approve the issuance of shares of SAIC common stock in the merger. At the special meeting of Engility stockholders scheduled on the same date, Engility stockholders will be asked to vote on (i) a proposal to adopt and approve the merger agreement, (ii) a proposal to approve the adjournment from time to time of the Engility special meeting if necessary to solicit additional proxies if there are not sufficient votes to adopt and approve the merger agreement at the time of the Engility special meeting or any adjournment or postponement thereof, and (iii) a proposal to approve, on an advisory (non-binding) basis, the compensation that may become payable to Engility’s named executive officers in connection with the merger.

We cannot complete the merger unless the Engility stockholders and the SAIC stockholders approve the respective proposals related to the merger. Your vote is very important, regardless of the number of shares you own. Whether or not you expect to attend the SAIC or Engility special meeting, as applicable, in person, please vote your shares as promptly as possible by (1) accessing the Internet website specified on your proxy card, (2) calling the toll-free number specified on your proxy card, or (3) signing and returning all proxy cards that you receive in the postage-paid envelope provided, so that your shares may be represented and voted at the SAIC or the Engility special meeting, as applicable. If you are an Engility stockholder, please note that a failure to vote your shares is the equivalent of a vote against the merger. If you are an SAIC stockholder, please note that a failure to vote your shares may result in a failure to establish a quorum for the SAIC special meeting.

The SAIC board of directors unanimously recommends that the SAIC stockholders vote “FOR” the proposal to issue shares of SAIC common stock in the merger. The Engility board of directors unanimously recommends that the Engility stockholders vote “FOR” the proposal to adopt and approve the merger agreement.

The obligations of SAIC and Engility to complete the merger are subject to the satisfaction or waiver of several conditions set forth in the merger agreement. More information about SAIC, Engility and the merger is contained in this joint proxy statement/prospectus. SAIC and Engility encourage you to read this entire joint proxy statement/prospectus carefully, including the section entitled “Risk Factors” beginning on page 25.

We look forward to the successful merger of SAIC and Engility.

Sincerely,	Sincerely,
Anthony J. Moraco	Lynn A. Dugle
Chief Executive Officer	Chairman, President and Chief Executive Officer
Science Applications International Corporation	Engility Holdings, Inc.

Neither the U.S. Securities and Exchange Commission nor any state securities commission has approved or disapproved of the securities to be issued under this joint proxy statement/prospectus or determined that this joint proxy statement/prospectus is accurate or complete. Any representation to the contrary is a criminal offense.

This joint proxy statement/prospectus is dated                   , 2018 and is first being mailed to the stockholders of SAIC and stockholders of Engility on or about                   , 2018.

Science Applications International Corporation
   
12010 Sunset Hills Road
Reston, VA 20190
(703) 676-4300

NOTICE OF SPECIAL MEETING OF STOCKHOLDERS TO BE HELD ON JANUARY 11, 2019

Dear SAIC stockholders:

We are pleased to invite you to attend the special meeting of the SAIC stockholders, which will be held at 12010 Sunset Hills Road, Reston, Virginia 20190, on January 11, 2019, at 9:00 a.m., local time, which we refer to as the SAIC special meeting, for the following purposes:

SAIC will transact no other business at the special meeting except such business as may properly be brought before the special meeting or any adjournment or postponement thereof. Please refer to the attached joint proxy statement/prospectus for further information with respect to the business to be transacted at the SAIC special meeting.

The SAIC board of directors (which we refer to as the SAIC Board) unanimously recommends that SAIC stockholders vote “FOR” the SAIC stock issuance proposal and “FOR” the SAIC adjournment proposal.

Holders of record of shares of SAIC common stock, at the close of business on November 29, 2018, which we refer to as the record date, are entitled to notice of, and may vote at, the special meeting and any adjournment of the special meeting. Beginning two business days after the date of this notice and continuing through the date of the special meeting, a list of these stockholders will be available for inspection at SAIC’s principal office by any SAIC stockholder for any purpose germane to such meeting.

Approval of the SAIC stock issuance proposal requires the approval by affirmative vote of a majority in voting interest of the holders of SAIC common stock present in person or by proxy entitled to vote on such matter at the SAIC special meeting (provided that a quorum exists). Approval of the SAIC adjournment proposal requires the affirmative vote of a majority of the votes cast at the SAIC special meeting by holders of shares of SAIC common stock (whether or not a quorum is present).

Your vote is important. Whether or not you expect to attend the SAIC special meeting in person, we urge you to vote your shares as promptly as possible by (1) accessing the Internet website specified on your proxy card; (2) calling the toll-free number specified on your proxy card; or (3) signing and returning the enclosed proxy card in the postage-paid envelope provided, so that your shares may be represented and voted at the SAIC special meeting. If your shares are held in the name of a bank, broker or other fiduciary, please follow the instructions on the voting instruction card furnished by the record holder. In lieu of receiving a proxy card, participants in certain benefit plans of SAIC and certain participating SAIC subsidiaries have been furnished with voting instruction cards, which are described in greater detail in the accompanying joint proxy statement/prospectus.

If you have any questions or need assistance voting your shares, please call our proxy solicitor, Georgeson, LLC, toll-free at (888) 658-3624 or as an international caller at (781) 575-2137.

	By Order of the Board of Directors,
	Steven G. Mahon Executive Vice President, General Counsel & Corporate Secretary

Reston, Virginia

         , 2018

Engility Holdings, Inc.
   
4803 Stonecroft Boulevard
Chantilly, VA 20151
(703)-633-8300

NOTICE OF SPECIAL MEETING OF STOCKHOLDERS TO BE HELD ON JANUARY 11, 2019

Dear Engility stockholders:

We are pleased to invite you to attend the special meeting of the Engility stockholders, which will be held at 4803 Stonecroft Boulevard, Chantilly, Virginia 20151 on January 11, 2019, at 9:00 a.m., local time, which we refer to as the Engility special meeting, for the following purposes:

Engility will transact no other business at the special meeting except such business as may properly be brought before the special meeting or any adjournment or postponement thereof. Please refer to the attached joint proxy statement/prospectus for further information with respect to the business to be transacted at the Engility special meeting.

The Engility board of directors (which we refer to as the Engility Board) unanimously recommends that Engility stockholders vote “FOR” the Engility merger proposal, “FOR” the Engility adjournment proposal and “FOR” the Engility compensation proposal.

Holders of record of shares of Engility common stock, at the close of business on November 29, 2018, which we refer to as the record date, are entitled to notice of, and may vote at, the special meeting and any adjournment of the special meeting. Beginning two business days after the date of this notice and continuing through the date of the special meeting, a list of these stockholders will be available for inspection at Engility’s principal office by any Engility stockholder for any purpose germane to such meeting.

Approval of the Engility merger proposal requires the affirmative vote of holders of a majority of the votes outstanding and entitled to vote on such matter at the Engility special meeting by holders of Engility common stock. Approval of the Engility adjournment proposal requires the affirmative vote of a majority of the votes cast at the Engility special meeting by holders of shares of Engility common stock (provided that a quorum exists). Approval of the Engility compensation proposal requires the affirmative vote of a majority of the votes cast at the Engility special meeting by holders of shares of Engility common stock (provided that a quorum exists).

Your vote is very important, regardless of the number of shares of Engility common stock you own. The merger cannot be completed unless stockholders of both Engility and SAIC approve certain proposals related to the merger. Whether or not you expect to attend the Engility special meeting in person, we urge you to vote your shares as promptly as possible by (1) accessing the Internet website specified on your proxy card; (2) calling the toll-free number specified on your

proxy card; or (3) signing and returning the enclosed proxy card in the postage-paid envelope provided, so that your shares may be represented and voted at the Engility special meeting. Properly executed proxy cards with no instructions indicated on the proxy card will be voted “FOR” the Engility merger proposal, “FOR” the Engility compensation proposal and “FOR” the Engility adjournment proposal. Even if you plan to attend the Engility special meeting in person, Engility requests that you complete, sign, date and return the enclosed proxy card in the accompanying envelope prior to the special meeting to ensure that your shares will be represented and voted at the special meeting if you are unable to attend.

If you attend the Engility special meeting, you may revoke your proxy and vote in person, even if you have previously returned your proxy card or submitted your proxy through the Internet or by telephone. If your shares are held in the name of a bank, broker or other fiduciary, please follow the instructions on the voting instruction card furnished by the record holder. In lieu of receiving a proxy card, participants in certain benefit plans of Engility have been furnished with voting instruction cards, which are described in greater detail in the accompanying joint proxy statement/prospectus. Please carefully review the instructions in the enclosed joint proxy statement/prospectus and the enclosed proxy card or the information forwarded by your broker, bank, trust or other nominee regarding each of these options.

We encourage you to read the enclosed joint proxy statement/prospectus carefully, including all its annexes and documents incorporated by reference, including the section entitled “Risk Factors” beginning on page 25. If you have any questions or need assistance voting your shares, please call our proxy solicitor, D.F. King & Co., Inc., toll-free at (800) 967-7510 or collect at (212) 269-5550.

	By Order of the Board of Directors,
	Thomas O. Miiller Senior Vice President, General Counsel and Corporate Secretary

Chantilly, Virginia

         , 2018

ADDITIONAL INFORMATION

This joint proxy statement/prospectus incorporates important business and financial information about SAIC and Engility from other documents that are not included in or delivered with this joint proxy statement/prospectus. This information is available to you without charge upon your request. You can obtain the documents incorporated by reference into this joint proxy statement/prospectus by requesting them in writing or by telephone from the appropriate company at the following addresses and telephone numbers:

Investors may also consult SAIC’s or Engility’s website for more information concerning the merger described in this joint proxy statement/prospectus. SAIC’s website is www.saic.com. Engility’s website is www.engility.com. Information included on these websites is not incorporated by reference into this joint proxy statement/prospectus.

In addition, if you have questions about the merger or the accompanying joint proxy statement/prospectus, would like additional copies of the joint proxy statement/prospectus, or need to obtain proxy cards or other information related to the proxy solicitation, please call Georgeson LLC, the proxy solicitor for SAIC, toll-free at (888) 658-3624 or as an international caller at (781) 575-2137, or D.F. King & Co., Inc., the proxy solicitor for Engility, toll-free at (800) 967-7510 or collect at (212) 269-5550. You will not be charged for any of these documents that you request.

If you would like to request any documents, please do so at least five business days before the special meeting in order to receive them before the special meetings.

For more information, see “Where You Can Find More Information” beginning on page 156.

ABOUT THIS DOCUMENT

This joint proxy statement/prospectus, which forms part of a registration statement on Form S-4 filed with the Securities and Exchange Commission, which we refer to as the SEC, by SAIC (File No. 333-227884), constitutes a prospectus of SAIC under Section 5 of the Securities Act of 1933, as amended, which we refer to as the Securities Act, with respect to the shares of SAIC common stock proposed to be issued to Engility stockholders under the merger agreement. This document also constitutes a joint proxy statement under Section 14(a) of the Securities Exchange Act of 1934, as amended, which we refer to as the Exchange Act. It also includes a notice of meeting with respect to the special meeting of SAIC stockholders, at which SAIC stockholders will be asked to vote upon the SAIC stock issuance proposal, and a notice of meeting with respect to the special meeting of Engility stockholders, at which Engility stockholders will be asked to vote upon a proposal to adopt and approve the merger agreement.

Before casting your vote, you should carefully review all the information contained or incorporated by reference into this joint proxy statement/prospectus. No one has been authorized to provide you with information that is different from that contained in, or incorporated by reference into, this joint proxy statement/prospectus. This joint proxy statement/prospectus is dated          , 2018. You should not assume that the information contained in, or incorporated by reference into, this joint proxy statement/prospectus is accurate as of any date other than the date on the front cover of those documents. Neither our mailing of this joint proxy statement/prospectus to SAIC stockholders or Engility stockholders nor the issuance by SAIC of common stock in connection with the merger will create any implication to the contrary.

In deciding how to vote with respect to any of the proposals discussed herein, you must make your own independent examination of the merits and risks of the proposal. You should not construe anything included in this joint proxy statement/prospectus as investment, legal, business or tax advice, and should consult with your own advisors if you have questions concerning any of the matters described herein.

This joint proxy statement/prospectus does not constitute an offer to sell, or a solicitation of an offer to buy, any securities, or the solicitation of a proxy, in any jurisdiction in which or from any person to whom it is unlawful to make any such offer or solicitation in such jurisdiction. Information contained in this joint proxy statement/prospectus regarding SAIC has been provided by SAIC and information contained in this joint proxy statement/prospectus regarding Engility has been provided by Engility.

All references in this joint proxy statement/prospectus to “Engility” refer to Engility Holdings, Inc. a Delaware corporation (except that in connection with the description of its operations or business under the headings “Cautionary Statement Regarding Forward-Looking Statements” and “Risk Factors,” such term refers to the consolidated operations of Engility and its subsidiaries); all references in this joint proxy statement/prospectus to “SAIC” refer to Science Applications International Corporation, a Delaware corporation (except that in connection with the description of its operations or business under the headings “Cautionary Statement Regarding Forward-Looking Statements” and “Risk Factors”, such term refers to the consolidated operations of SAIC and its subsidiaries); and all references to “merger sub” refer to Raptors Merger Sub, Inc., a Delaware corporation and a direct wholly owned subsidiary of SAIC, formed for the purpose of effecting the merger. Unless otherwise indicated or as the context requires, all references to the “merger agreement” refer to the Agreement and Plan of Merger, dated as of September 9, 2018, among Engility, SAIC, and Raptors Merger Sub, Inc., a copy of which is included as Annex A to this joint proxy statement/prospectus.

TABLE OF CONTENTS

QUESTIONS AND ANSWERS

The following are answers to some questions that you, as a stockholder of SAIC or stockholder of Engility, may have regarding the merger and the other matters being considered at the SAIC special meeting and at the Engility special meeting. SAIC and Engility urge you to read carefully the remainder of this joint proxy statement/prospectus because the information in this section does not provide all the information that might be important to you with respect to the merger and the other matters being considered at the special meetings. Additional important information is also contained in the annexes to and the documents incorporated by reference into this joint proxy statement/prospectus.

In order to complete the merger, among other things:

SAIC is holding a special meeting of stockholders, which is referred to as the SAIC special meeting, in order to obtain the stockholder approval necessary to approve the stock issuance. SAIC stockholders will also be asked to approve the adjournment from time to time of the SAIC special meeting if necessary to solicit additional proxies if there are not sufficient votes at the time of the SAIC special meeting, or any adjournment or postponement thereof, to approve the stock issuance, which is referred to as the SAIC adjournment proposal.

Engility is holding a special meeting of stockholders to obtain their approval to adopt and approve the merger agreement. In addition, Engility stockholders will also be asked to approve the adjournment from time to time of the Engility special meeting if necessary to solicit additional proxies if there are not sufficient votes to adopt and approve the merger agreement at the time of the Engility special meeting or any adjournment or postponement thereof, which is referred to as the Engility adjournment proposal, and to approve, on an advisory (non-binding) basis, the compensation that may be paid or become payable to Engility’s named executive officers, who are referred to as the named executive officers, in connection with the merger, which is referred to as the Engility compensation proposal. It is important that Engility stockholders vote their Engility common shares on each of these matters, regardless of the number of shares owned.

Your vote is important. We encourage you to vote as soon as possible.

If the merger is completed, Engility stockholders will have the right to receive 0.450 of a share of SAIC common stock for each share of Engility common stock they own at closing, which we refer to as the exchange ratio, with cash paid in lieu of fractional shares. The exchange ratio is fixed and will not be adjusted to reflect stock price changes prior to closing of the merger.

SAIC stockholders will not receive any merger consideration and will continue to hold their shares of SAIC common stock.

Based on the closing price of SAIC common stock on the New York Stock Exchange (which we refer to as the NYSE) of $89.86 on September 7, 2018, the last trading day before public announcement of the transaction, the merger consideration represented approximately $40.44 of aggregate value for each share of Engility common stock. Based on the SAIC closing price of $69.52 on November 29, 2018, the latest practicable date before the date of this joint proxy statement/prospectus, the merger consideration represented approximately $31.28 of aggregate value for each share of Engility common stock.

SAIC stockholders will continue to own their existing SAIC shares. SAIC common stock is currently traded on the NYSE under the symbol “SAIC,” and Engility common stock is currently traded on the NYSE under the symbol “EGL.”

We encourage you to obtain current market quotations of SAIC common stock and Engility common stock before voting.

If you hold shares of SAIC common stock or shares of Engility common stock in the name of a broker or nominee, please follow the voting instructions provided by your broker or nominee to ensure that your shares are represented at your special meeting. If you received voting instruction cards from a trustee of any retirement plan of SAIC, Engility, or their subsidiaries in which you are a participant, please follow the instructions on those cards to ensure that shares of stock allocated to your plan account are represented at your special meeting.

If you are an Engility stockholder of shares not held in the Engility Master Savings Plan, the deadline for submitting a proxy using the Internet or the telephone is 11:59 p.m. Eastern time on January 10, 2019. If you received your special meeting materials by mail, you may complete, sign and date the proxy card or voting instruction card and return it in the prepaid envelope. All

stockholders as of the close on business on the record date may vote in person at the Engility special meeting. If your shares are held in the Engility Master Savings Plan, the deadline for submitting voting instructions using any of the allowed methods is 11:59 p.m. Eastern time on January 8, 2019. For detailed information, see the section entitled “The Engility Special Meeting.”

Adjournment Proposal. Approval of any SAIC adjournment proposal, if necessary, requires the approval by affirmative vote of a majority in voting interest of the holders of SAIC common stock present in person or by proxy entitled to vote on such matter at the SAIC special meeting (provided that a quorum exists). For any adjournment proposal, an abstention will have the effect of a vote against the proposal. Broker “non-votes” will have no effect on the outcome of the proposal. Shares of

SAIC common stock represented by properly executed, timely received and unrevoked proxies will be voted in accordance with the instructions indicated thereon. In the absence of specific instructions, properly executed, timely received and unrevoked proxies will be voted “FOR” each proposal.

Compensation Proposal. Approval of the non-binding Engility compensation proposal requires the affirmative vote of a majority of the votes cast on such matter at the Engility special meeting by holders of the Engility common stock (provided that a quorum exists). For the Engility compensation proposal, an abstention will have no effect on the outcome of the proposal. Broker “non-votes” will also have no effect on the outcome of the proposal. Shares of Engility common stock represented by properly executed, timely received and unrevoked proxies will be voted in accordance with the instructions indicated thereon. In the absence of specific instructions, properly executed, timely received and unrevoked proxies will be voted “FOR” each proposal.

Adjournment Proposal. Approval of any Engility adjournment proposal, if necessary, requires the affirmative vote of a majority of the votes cast on such matter at the Engility special meeting by holders of the Engility common stock (provided that a quorum exists). For any adjournment proposal, an abstention will have no effect on the outcome of the proposal. Broker “non-votes” will also have no effect on the outcome of the proposal. Shares of Engility common stock represented by properly executed, timely received and unrevoked proxies will be voted in accordance with the instructions indicated thereon. In the absence of specific instructions, properly executed, timely received and unrevoked proxies will be voted “FOR” each proposal.

Engility. You are entitled to one vote for each share of Engility common stock that you owned as of the record date. As of the close of business on November 29, 2018, there were 36,968,909 outstanding shares of Engility common stock. As of that date, less than 1% of the outstanding shares of Engility common stock were beneficially owned by the directors and executive officers of Engility.

Engility. If you are an Engility stockholder and fail to vote, fail to instruct your broker or nominee to vote, or abstain from voting, it will have the same effect as a vote against the Engility merger proposal. For purposes of the Engility compensation proposal and the Engility adjournment proposal, a failure to vote, failure to instruct, or abstention from voting will have no effect on the approval of the proposal (provided that a quorum exists).

Engility. Stockholders who hold a majority of the total number of shares of Engility common stock issued and outstanding as of the close of business on the record date must be present or represented by proxy to constitute a quorum to conduct the Engility special meeting. All shares of Engility common stock represented at the Engility special meeting, including abstentions and broker non-votes (shares held by a broker or nominee that are represented at the meeting, but with respect to which the broker or nominee is not instructed by the beneficial owner of such shares to vote on the particular proposal), will be treated as present for purposes of determining the presence or absence of a quorum to conduct the Engility special meeting, but abstentions and broker non-votes will be treated as not present for purposes of determining the presence or absence of a quorum with respect to the Engility merger proposal.

Please follow the voting instructions provided by your broker or nominee. Please note that you may not vote shares held in street name by returning a proxy card directly to SAIC or Engility or by voting in person at your special meeting. Further, brokers who hold shares of SAIC common stock or Engility common stock on behalf of their customers may not give a proxy to SAIC or Engility to vote those shares without specific instructions from their customers.

If you choose either of the first two methods, you must submit your notice of revocation or your new proxy to the Secretary of SAIC or Secretary of Engility, as applicable, no later than the beginning of the applicable special meeting. If your shares are held in street name by your broker or nominee, you should contact them to change your vote. If your shares are held through an SAIC or Engility retirement plan, you should contact the trustee for the plan to change your vote.

Treatment of Performance Stock Unit Awards. At the effective time, each outstanding Engility performance stock unit will be converted into a time-based vesting restricted stock unit for a number of whole shares of SAIC common stock (rounded up to the nearest whole share) equal to the product of (a) the number of shares of Engility common stock subject to such award determined based on (x) target performance (if the effective time occurs on or prior to December 31, 2018) or (y) actual performance measured on the effective time (or December 31, 2018 if determined by the compensation committee of Engility) if more than twelve months have elapsed from the beginning of the performance period of the applicable performance stock units to the effective time, and (b) the exchange ratio, subject to vesting based on continued service until the third anniversary of the grant date of the Engility performance stock unit, and other terms and conditions, including vesting acceleration terms, as were applicable to such awards prior to the merger.

we refer to as the Code). If the merger qualifies for such intended tax treatment, a U.S. holder of Engility common stock generally will not recognize any gain or loss for U.S. income tax purposes upon the exchange of such holder’s shares of Engility common stock for shares of SAIC common stock in the merger, except that such holder of Engility common stock generally may recognize gain or loss with respect to cash received in lieu of a fractional share of SAIC common stock.

As further described in the section entitled “The Merger Agreement—Conditions to Completion of the Merger”, Engility’s obligation to effect the merger is subject to the satisfaction, or waiver by Engility, at or prior to the effective time of the merger, of the condition that Engility receive a written tax opinion from Weil, Gotshal & Manges LLP, legal counsel to Engility, dated as of the closing date of the merger, to the effect that the merger will qualify as a “reorganization” within the meaning of Section 368(a) of the Code. In the event that Weil, Gotshal & Manges LLP does not render such tax opinion, and Engility does not otherwise waive this condition, the condition may be satisfied if Morrison & Foerster LLP, legal counsel to SAIC, renders such tax opinion.

You should read the section entitled “Material U.S. Federal Income Tax Consequences” beginning on page 124 for a more complete discussion of the U.S. federal income tax consequences of the merger. Tax matters can be complicated, and the tax consequences of the merger to you will depend on your particular situation. You should consult your tax advisor to determine the tax consequences of the merger to you.

In order for your shares to be represented at your special meeting:

If you are an SAIC stockholder, you are not required to take any action with respect to your SAIC stock certificates.

Under Delaware law, the SAIC stockholders are not entitled to appraisal rights in connection with the SAIC stock issuance proposal.

SUMMARY

This summary highlights information contained elsewhere in this joint proxy statement/prospectus and may not contain all the information that is important to you. SAIC and Engility urge you to read carefully the remainder of this joint proxy statement/prospectus, including the attached annexes, and the other documents to which we have referred you because this section does not provide all the information that might be important to you with respect to the merger and the related matters being considered at the applicable special meeting. See also the section entitled “Where You Can Find More Information” on page 156. We have included page references to direct you to a more complete description of the topics presented in this summary.

The Companies

SAIC (See page 33)

Science Applications International Corporation
12010 Sunset Hills Road
Reston, VA 20190
(703) 676-4300

SAIC is a leading provider of technical, engineering and enterprise information technology (IT) services primarily to the U.S. government. SAIC provides engineering, systems integration and information technology offerings for large, complex government projects and offer a broad range of services with a targeted emphasis on higher-end, differentiated technology services. SAIC’s end-to-end enterprise IT offerings span the entire spectrum of its customers' IT infrastructure. SAIC commenced operations on September 27, 2013 following completion of a spin-off transaction from its former parent, Leidos Holdings, Inc. In May 2015 SAIC completed the acquisition of privately held Scitor Holdings, Inc., a leading provider of services to the intelligence community, which enabled SAIC to gain sufficient scale to competitively pursue opportunities within the intelligence community.

SAIC’s business has a long and successful history, tracing its roots to the earliest days of its former parent, Leidos Holdings, Inc., which was founded in 1969 as a scientific research and engineering firm. The U.S. federal government agencies SAIC serves include all branches of the U.S. military (Army, Air Force, Navy, Marines and Coast Guard), U.S. Defense Logistics Agency, National Aeronautics and Space Administration (NASA), U.S. Department of State, and U.S. Department of Homeland Security (DHS). SAIC’s long-standing customer relationships have enabled it to achieve an in-depth understanding of its customers’ missions and provide differentiated service offerings to meet its customers’ most complex requirements. SAIC’s offerings include: engineering; technology and equipment platform integration; maintenance of ground and maritime systems; logistics; training and simulation; operation and program support services; and end-to-end services spanning the design, development, integration, deployment, management and operations, sustainment and security of its customers’ entire IT infrastructure. SAIC serves its customers through approximately 1,300 active contracts and task orders. SAIC has more than 15,000 individuals that are led by an experienced executive team of proven industry leaders. Substantially all of our revenues and tangible long-lived assets are generated by or owned by entities located in the United States.

SAIC is organized as a matrix comprised of three customer facing operating segments supported by three market service line organizations. The three operating segments are responsible for customer relationships, business development and program management, and delivery and execution, while the market service line organizations manage our workforce and the development of SAIC’s offerings, solutions and capabilities. Each of SAIC’s three operating segments is focused on providing comprehensive technical, engineering and enterprise IT service offerings to one or more agencies of the U.S federal government. SAIC's operating segments are aggregated into one reportable segment for financial reporting purposes.

Raptors Merger Sub, Inc. (See page 34)

Raptors Merger Sub, Inc.
12010 Sunset Hills Road
Reston, VA 20190
(703) 676-4300

Raptors Merger Sub, Inc., a direct wholly owned subsidiary of SAIC, is a Delaware corporation formed on September 5, 2018 for the purpose of effecting the merger. Upon completion of the merger, merger sub will be merged with and into Engility with Engility surviving as a direct wholly owned subsidiary of SAIC.

Merger sub has not conducted any activities other than those incidental to its formation and the matters contemplated by the merger agreement, including the preparation of applicable regulatory filings in connection with the merger.

Engility (See page 34)

Engility Holdings, Inc.
4803 Stonecroft Boulevard
Chantilly, VA 20151
(703) 633-8300

Engility is a leading provider of integrated solutions and services, supporting U.S. government customers in the defense, federal civilian, intelligence and space communities. Engility offers a broad range of highly technical services, leveraging its strengths in systems engineering, cybersecurity, high performance computing, enterprise modernization, and training and mission operations to solve customers’ most difficult challenges. Engility is headquartered in Chantilly, Virginia, and maintains offices around the world.

Engility was formed as a result of its spin-off from L3 Technologies (formerly, L-3 Communications Holdings, Inc.) in July 2012. Engility has provided mission critical services to the U.S. government for more than 60 years. During the past five years, Engility completed two transformative acquisitions – Dynamics Research Corporation (DRC) in 2014 and TASC, Inc. (TASC) in 2015. These acquisitions enabled Engility to diversify its customer base and capabilities, add substantial scale to its business and increase its addressable market.

During 2017, Engility streamlined its operating structure around three business groups – Intelligence Solutions, Space and Mission Systems and Defense and Security – to improve customer intimacy, enhance employee collaboration, and drive efficiencies throughout the organization so Engility could further invest in growth-related activities. These groups serve a broad range of customers, including the U.S. Department of Defense (DoD), U.S. Department of Justice (DoJ), U.S. Department of State (DoS), Federal Aviation Administration (FAA), Department of Homeland Security (DHS), and space-related and intelligence community agencies, including the Central Intelligence Agency (CIA), the National Security Agency (NSA), the National Geospatial-Intelligence Agency (NGA), Defense Intelligence Agency (DIA), the National Reconnaissance Office (NRO), National Aeronautical and Space Administration (NASA) and U.S. Air Force Space Command (AFSPC).

Risk Factors

Before voting at the SAIC special meeting or the Engility special meeting, you should carefully consider all of the information contained in or as incorporated by reference into this joint proxy statement/prospectus, as well as the specific factors under the heading “Risk Factors” beginning on page 25 of this joint proxy statement/prospectus.

The Merger and the Merger Agreement

A copy of the merger agreement is attached as Annex A to this joint proxy statement/prospectus. SAIC and Engility encourage you to read the entire merger agreement carefully because it is the principal document governing the merger. For more information on the merger agreement, see the section entitled “The Merger Agreement” beginning on page 100.

Effect of the Merger

Subject to the terms and conditions of the merger agreement, at the effective time of the merger, merger sub will be merged with and into Engility, with Engility continuing as a direct wholly owned subsidiary of SAIC.

Merger Consideration

If the merger is completed, Engility stockholders will have the right to receive 0.450 of a share of SAIC common stock for each share of Engility common stock they own at closing, which we refer to as the exchange ratio, with cash paid in lieu of fractional shares. The exchange ratio is fixed and will not be adjusted to reflect stock price changes prior to closing of the merger.

SAIC stockholders will not receive any merger consideration and will continue to hold their shares of SAIC common stock.

The value of the merger consideration that Engility stockholders receive will depend on the price per share of SAIC common stock at the effective time of the merger. That price will not be known at the time of the special meetings and may be more or less than the current price or the price at the time of the special meetings. This exchange ratio will not be adjusted for changes in the market price of either SAIC common stock or Engility common stock between the date of signing the merger agreement and completion of the merger.

Based on the closing price of SAIC common stock on the NYSE of $89.86 on September 7, 2018, the last trading day before public announcement of the transaction, the merger consideration represented approximately $40.44 of aggregate value for each share of Engility common stock. Based on the SAIC closing price of $69.52 on November 29, 2018, the latest practicable date before the date of this joint proxy statement/prospectus, the merger consideration represented approximately $31.28 of aggregate value for each share of Engility common stock.

Treatment of Engility Equity Awards (See page 111)

Treatment of Restricted Stock Unit Awards. At the effective time, each outstanding Engility restricted stock unit, whether vested or unvested, will be converted into a restricted stock unit for a number of whole shares of SAIC common stock (rounded to the nearest whole share) equal to the product of (a) the number of shares of Engility common stock subject to such award and (b) the SAIC equity award exchange ratio, subject to the same terms and conditions, including vesting, as were applicable to such awards prior to the merger.

Treatment of Performance Stock Unit Awards. At the effective time, each outstanding Engility performance stock unit will be converted into a time-based vesting restricted stock unit for a number of whole shares of SAIC common stock (rounded up to the nearest whole share) equal to the product of (a) the number of shares of Engility common stock subject to such award determined based on (x) target performance (if the effective time occurs on or prior to December 31, 2018) or (y) actual performance measured on the effective time (or December 31, 2018 if determined by the compensation committee of Engility) if more than twelve months have elapsed from the beginning of the performance period of the applicable performance stock units to the effective time, and (b) the exchange ratio, subject to vesting based on continued service until the third anniversary of the grant date of the Engility performance stock unit, and other terms and conditions, including vesting acceleration terms, as were applicable to such awards prior to the merger.

Material U.S. Federal Income Tax Consequences of the Merger (See page 124)

It is intended that, for U.S. federal income tax purposes, the merger will qualify as a “reorganization” within the meaning of Section 368(a) of the Code. If the merger qualifies for such intended tax treatment, a U.S. holder of Engility common stock generally will not recognize any gain or loss for U.S. federal income tax purposes upon the exchange of such holder’s shares of Engility common stock for shares of SAIC common stock in the merger, except that such holder of Engility common stock generally may recognize gain or loss with respect to cash received in lieu of a fractional share of SAIC common stock.

As further described in the section entitled “The Merger Agreement—Conditions to Completion of the Merger”, Engility’s obligation to effect the merger is subject to the satisfaction, or waiver by Engility, at or prior to the effective time of the merger, of the condition that Engility receive a written tax opinion from Weil, Gotshal & Manges LLP, legal counsel to Engility, dated as of the closing date of the merger, to the effect that the merger will qualify as a “reorganization” within the meaning of Section 368(a) of the Code. In the event that Weil, Gotshal & Manges LLP does not render such tax opinion, and Engility does not otherwise waive this condition, the condition may be satisfied if Morrison & Foerster LLP, legal counsel to SAIC, renders such tax opinion.

The discussion of U.S. federal income tax consequences of the merger contained in this proxy statement/prospectus is intended to provide only a general summary and is not a complete analysis or description of all potential U.S. federal income tax consequences of the merger. The discussion does not address tax consequences that may vary with, or are contingent on, individual circumstances. In addition, it does not address the effects of any non-U.S., state or local tax laws.

For a more complete discussion of the material U.S. federal income tax consequences of the merger, please carefully review the information set forth in the section entitled “Material U.S. Federal Income Tax Consequences”.

The tax consequences of the merger to any particular stockholder will depend on that stockholder’s particular facts and circumstances. Accordingly, you are urged to consult your own tax advisor as to the specific tax consequences of the merger, including the effects of U.S. federal, state or local, non-U.S. and other tax laws.

Recommendations of the SAIC Board (See page 52)

After careful consideration, the SAIC Board, on September 9, 2018, unanimously approved the merger agreement and determined that the merger agreement and the transactions contemplated thereby, including the SAIC stock issuance, are in the best interests of SAIC and its stockholders. For the factors considered by the SAIC Board in reaching its decision to approve the merger agreement, see the section entitled “The Merger and the Stock Issuance—SAIC’s Reasons for the Merger; Recommendation of the Stock Issuance by the SAIC Board” beginning on page 52. The SAIC Board unanimously recommends that the SAIC stockholders vote “FOR” the proposal to issue shares of SAIC common stock in connection with the merger.

Recommendation of the Engility Board (See page 53)

After careful consideration, the Engility Board, on September 9, 2018, unanimously approved and adopted the merger agreement and determined that the merger agreement and the transactions contemplated thereby, including the merger, are advisable and in the best interests of Engility and its stockholders. For the factors considered by the Engility Board in reaching its decision to approve and adopt the merger agreement, see the section entitled “The Merger and the Stock Issuance—Engility’s Reasons for the Merger; Recommendation of the Merger by the Engility Board” beginning on page 53 of this joint proxy statement/prospectus. The Engility Board unanimously recommends that the Engility stockholders vote “FOR” the Engility merger proposal.

Opinions of SAIC’s Financial Advisors (See page 57)

Opinion of Citigroup Global Markets Inc.

In connection with the merger, SAIC’s financial advisor, Citigroup Global Markets Inc., which we refer to as Citi, rendered an oral opinion to the SAIC Board at its September 9, 2018 meeting as to the fairness, from a financial point of view and as of the date of the opinion, to SAIC of the exchange ratio, which was confirmed by delivery of a written opinion dated September 9, 2018. The full text of Citi’s written opinion, dated September 9, 2018, which describes the assumptions made, procedures followed, matters considered, and limitations and qualifications on the review undertaken, is attached as Annex C to this joint proxy statement/prospectus and is incorporated into this joint proxy statement/prospectus by reference. The description of Citi’s opinion set forth below is qualified in its entirety by reference to the full text of Citi’s opinion. Citi’s opinion was provided for the information of the SAIC Board (in its

capacity as such) in connection with its evaluation of the exchange ratio from a financial point of view to SAIC and did not address any other terms, aspects or implications of the merger. Citi expressed no view as to, and its opinion did not address, the underlying business decision of SAIC to effect the merger, the relative merits of the merger as compared to any alternative business strategies or transactions that might exist for SAIC or the effect of or on any other transaction which SAIC might engage. Citi’s opinion is not intended to be and does not constitute a recommendation to any stockholder as to how such stockholder should vote or act on any matters relating to the proposed merger or any related matter.

For a description of the opinion that the SAIC Board received from Citi, see the section entitled “The Merger and the Stock Issuance—Opinions of SAIC’s Financial Advisors—Opinion of Citi” beginning on page 57.

Opinion of Stone Key

In connection with the merger, Stone Key Partners LLC and Stone Key Securities LLC, which we refer to as Stone Key, financial advisor to SAIC, delivered to the SAIC Board an oral opinion, which was subsequently confirmed by delivery of a written opinion, dated September 9, 2018, to the effect that, as of the date of the opinion and based on and subject to the assumptions, qualifications and limitations set forth in the written opinion, the exchange ratio was fair, from a financial point of view, to SAIC.

The full text of Stone Key’s written opinion, which describes, among other things, the assumptions made, some of the matters considered and qualifications to and limitations of the review undertaken by Stone Key, is attached as Annex B to this document. The Stone Key opinion is subject to the assumptions, limitations, qualifications and other conditions contained in the opinion and is necessarily based on economic, market and other conditions and the information made available to Stone Key as of the date of the Stone Key opinion. Stone Key has no responsibility for updating or revising its opinion based on circumstances or events occurring after the date of the rendering of the opinion. The summary of Stone Key’s opinion contained in this joint proxy statement/prospectus is qualified in its entirety by reference to the full text of the opinion. Stone Key provided its opinion to the SAIC Board (solely in its capacity as such) for the benefit and use of the SAIC Board in connection with its consideration of the exchange ratio from a financial point of view. Stone Key’s opinion does not address any other term or aspect of the merger and no opinion or view was expressed as to the relative merits of the merger as compared to any alternative business or financial strategies that might exist for SAIC, the financing of the merger or the effects of any other transaction in which SAIC might engage or as to the underlying business decision of SAIC to pursue the merger. Stone Key’s opinion does not address any other aspect of the merger and does not constitute a recommendation to any stockholder of SAIC as to how to vote or act in connection with the proposed merger or any other matter.

For a more complete description of the opinion that the SAIC Board received from Stone Key, see the section entitled “The Merger and the Stock Issuance—Opinions of SAIC’s Financial Advisors—Opinion of Stone Key” beginning on page 64.

Opinion of Engility’s Financial Advisor (See page 72)

Opinion of Guggenheim Securities

Engility retained Guggenheim Securities, LLC (which we refer to as Guggenheim Securities) as its financial advisor in connection with the potential sale of, or another extraordinary corporate transaction with or involving, Engility. Guggenheim Securities delivered an opinion to Engility’s board of directors to the effect that, as of September 9, 2018, and based on and subject to the matters considered, the procedures followed, the assumptions made and various limitations of and qualifications to the review undertaken, the exchange ratio in connection with the merger was fair, from a financial point of view, to the stockholders of Engility. The full text of Guggenheim Securities’ written opinion, which is attached as Annex E to this joint proxy statement/prospectus and which you should read carefully and in its entirety, is subject to the assumptions, limitations, qualifications and other conditions contained in such opinion and is necessarily based on economic, capital markets and other conditions, and the information made available to Guggenheim Securities, as of the date of such opinion.

Guggenheim Securities’ opinion was provided to Engility’s board of directors (in its capacity as such) for its information and assistance in connection with its evaluation of the exchange ratio. Guggenheim Securities’ opinion and any materials provided in connection therewith did not constitute a recommendation to Engility’s board of directors with respect to the merger, nor does Guggenheim Securities’ opinion constitute advice or a recommendation to any holder of Engility or SAIC common stock as to how to vote or act in connection with the merger or otherwise. Guggenheim Securities’ opinion does not address Engility’s underlying business or financial decision to pursue the merger, the relative merits of the merger as compared to any alternative business or financial strategies that might exist for Engility or the effects of any other transaction in which Engility might engage. Guggenheim Securities’ opinion addresses only the fairness, from a financial point of view and as of the date of such opinion, of the exchange ratio to the stockholders of Engility. Guggenheim Securities did not express any view or opinion as to (i) any other term, aspect or implication of (a) the merger (including, without limitation, the form or structure of the merger) or the merger agreement or (b) the voting agreement or any other agreement, transaction document or instrument contemplated by the merger agreement or the voting agreement or to be entered into or amended in connection with the merger or (ii) the fairness, financial or otherwise, of the merger to, or of any consideration to be paid to or received by, the holders of any class of securities, creditors or other constituencies of Engility. Furthermore, Guggenheim Securities did not express any view or opinion as to the fairness, financial or otherwise, of the amount or nature of any compensation payable to or to be received by any of Engility’s or SAIC’s directors, officers or employees, or any class of such persons, in connection with the merger relative to the exchange ratio or otherwise.

For a description of the opinion that Engility’s board of directors received from Guggenheim Securities, see “The Merger — Opinion of Engility’s Financial Advisor” beginning on page 72.

Engility’s Executive Officers and Directors Have Financial Interests in the Merger That Differ from the Interests of Engility Stockholders (See page 85)

Certain members of the Engility Board and certain executive officers of Engility may be deemed to have financial interests in the merger that are in addition to, or different from, the interests of other Engility stockholders generally. The Engility Board was aware of these interests and considered them, among other matters, in approving the merger and the merger agreement and in making the recommendations that Engility stockholders approve and adopt the merger agreement. These interests include:

For additional details about these interests, see “Financial Interests of Engility Directors and Officers in the Merger” beginning on page 85.

Governance Matters After the Merger (See page 110)

At the effective time of the merger, SAIC shall cause its board of directors to consist of eleven members. SAIC shall appoint two individuals who are currently members of the Engility Board to serve on the board of directors of SAIC, to be mutually agreed upon by SAIC and Engility. SAIC and Engility have agreed that these directorships shall be filled by David M. Kerko and Katharina G. McFarland, each of whom is currently a director of Engility.

Following closing, Anthony Moraco is expected to continue in his current role as Chief Executive Officer of SAIC.

Regulatory Approvals Required for the Merger (See page 95)

As more fully described in this joint proxy statement/prospectus, the completion of the merger is subject to the expiration or earlier termination of the waiting period (and any extension thereof) applicable to the merger under the Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended, which we refer to as the HSR Act. The 30-day waiting period required by the HSR Act expired on October 22, 2018.

Litigation Related to the Merger (see page 98)

Following the initial filing of this joint proxy statement/prospectus on October 18, 2018, four lawsuits related to the merger were filed by SAIC and Engility stockholders, three of which are purported class actions. For additional details about these lawsuits, see “Litigation Related to the Merger” on page 98 of this joint proxy statement/prospectus.

Conditions to Completion of the Merger (See page 112)

As more fully described in this joint proxy statement/prospectus and in the merger agreement, the completion of the merger depends on a number of conditions being satisfied or, where legally permissible, waived. These conditions include, among others, receipt of the requisite approvals of SAIC stockholders and Engility stockholders, the expiration or early termination of the waiting period under the HSR Act, the absence of any law or order prohibiting the merger, the shares of SAIC common stock to be issued in connection with the merger having been approved for listing on the NYSE, the effectiveness of the registration statement of which this joint proxy statement/prospectus forms a part, the correctness of all representations and warranties made by the parties in the merger agreement and performance by the parties of their obligations under the merger agreement (subject in each case to certain materiality standards), no material adverse effect having occurred with respect to SAIC or Engility, and the receipt of a legal opinion from Engility’s tax counsel regarding the qualification of the merger as a reorganization for U.S. federal income tax purposes.

We cannot be certain when, or if, the conditions to the merger will be satisfied or waived, or that the merger will be completed.

Termination of the Merger Agreement (See page 114)

At any time before the effective time of the merger, whether before or after SAIC and Engility’s respective stockholder votes, either party may terminate the merger agreement:

At any time before the effective time of the merger, either party may terminate the merger agreement:

If, prior to the time the SAIC stockholder approval is obtained, (i) SAIC effects a change in recommendation, (ii) SAIC fails to include the SAIC Board recommendation in this joint proxy statement/prospectus, or (iii) SAIC materially breaches or fails to perform the non-solicitation provisions of the merger agreement, then Engility may terminate the merger agreement.

If, prior to the time the Engility stockholder approval is obtained, (i) the Engility Board effects a change in recommendation, (ii) Engility fails to include the Engility Board recommendation in this joint proxy statement/prospectus, or (iii) Engility materially breaches or fails to perform the non-solicitation provisions of the merger agreement, then SAIC may terminate the merger agreement.

Expenses and Termination Fees (See page 115)

Accounting Treatment (See page 127)

SAIC prepares its consolidated financial statements in accordance with accounting principles generally accepted in the United States, which we refer to as GAAP. The merger will be accounted for by applying the acquisition method with SAIC treated as the acquirer. Please see the section entitled “Accounting Treatment” on page 127 of this joint proxy statement/prospectus.

Appraisal Rights (See page 153)

Under Delaware law, the holders of Engility common stock are not entitled to appraisal rights in connection with the Engility merger proposal.

Under Delaware law, the holders of SAIC common stock are not entitled to appraisal rights in connection with the SAIC stock issuance proposal.

The SAIC Special Meeting

The SAIC special meeting will be held at 12010 Sunset Hills Road, Reston, Virginia 20190 at 9:00 a.m., local time, on January 11, 2019. At the SAIC special meeting, SAIC stockholders will be asked to approve:

You may vote at the SAIC special meeting if you owned shares of SAIC common stock at the close of business on November 29, 2018. You may cast one vote for each share of common stock of SAIC that you owned on the record date. On that date, there were 42,368,119 shares of common stock of SAIC outstanding and entitled to vote.

Approval of the SAIC stock issuance proposal requires the approval by affirmative vote of a majority in voting interest of the holders of SAIC common stock present in person or by proxy entitled to vote on such matters at the SAIC special meeting (provided that a quorum exists). Approval of the SAIC adjournment proposal requires approval by the affirmative vote of a majority of the votes cast on such matter at such meeting (provided that a quorum exists).

On the record date, less than 2% of the outstanding shares of SAIC common stock were held by SAIC directors and executive officers and their affiliates. SAIC currently expects that SAIC’s directors and executive officers will vote their shares in favor of the issuance of SAIC common stock in the merger.

The Engility Special Meeting

The Engility special meeting will be held at 4803 Stonecroft Boulevard, Chantilly, Virginia 20151, at 9:00 a.m., local time, on January 11, 2019. At the Engility special meeting, Engility stockholders will be asked:

You may vote at the Engility special meeting if you owned shares of Engility common stock at the close of business on November 29, 2018, the record date. As of the close of business on the record date, there were shares of common stock of Engility outstanding and entitled to vote. You may cast one vote for each share of Engility common stock that you owned on the record date.

Completion of the merger is conditioned on the approval of the Engility merger proposal. Approval of the Engility merger proposal requires the affirmative vote of holders of a majority of the outstanding shares of Engility common stock entitled to vote at the Engility special meeting. Approval of the Engility adjournment proposal and the Engility compensation proposal each requires the affirmative vote of holders of a majority of votes cast on such matter at the Engility special meeting by holders of Engility common stock (provided that a quorum exists).

On the record date for the Engility special meeting, the directors and executive officers of Engility and their affiliates owned and were entitled to vote 195,008 shares of Engility’s common stock, representing less than 1% of the outstanding Engility common stock. Engility currently expects that Engility’s directors and executive officers will vote their shares in favor of the Engility merger proposal, the Engility compensation proposal and the Engility adjournment proposal.

Birch entered into the voting agreement with SAIC and Engility and, for purposes of certain sections thereof, certain investment funds affiliated with KKR and certain investment funds affiliated with GA. Birch owns 17,920,892 covered shares (or approximately 48.48% of the total outstanding shares, of Engility common stock as of September 5, 2018). Subject to the terms and conditions set forth in the voting agreement, Birch has agreed, among other things, to vote the covered shares in favor of the adoption of the merger agreement to fullest extent Birch is permitted to do so under the stockholders agreement. Pursuant to the stockholders agreement, Birch is entitled to vote 30% of the total outstanding shares of Engility common stock in favor of the adoption of the merger agreement. In addition, under the stockholders agreement, Birch is obligated to vote its shares of Engility common stock in excess of 30% of the total outstanding shares of Engility common stock in the same manner as, and in the same proportion to, all shares of Engility common stock voted by holders of Engility common stock (excluding those votes of Birch that represent up to 30% of all issued and outstanding shares of Engility common stock).

SELECTED HISTORICAL CONSOLIDATED FINANCIAL DATA OF SAIC

The following tables set forth selected consolidated financial information for SAIC. The selected statement of income data for the six months ended August 3, 2018 and August 4, 2017 and the selected balance sheet data as of August 3, 2018 and August 4, 2017 have been derived from SAIC’s unaudited consolidated financial statements. In the opinion of SAIC’s management, all adjustments considered necessary for a fair presentation of the interim financial information have been included. The selected statement of income data for each of the five preceding fiscal years, and the selected balance sheet data as of the end of each corresponding fiscal year have been derived from SAIC’s consolidated financial statements that were audited by Deloitte & Touche LLP. The following information should be read together with SAIC’s consolidated financial statements, the notes related thereto and management’s related reports on SAIC’s financial condition and performance, all of which are contained in SAIC’s Annual Report on Form 10-K for the year ended February 2, 2018 and in subsequent reports filed with the SEC, which are incorporated herein by reference. See “Where You Can Find More Information” on page 156 of this joint proxy statement/prospectus. The operating results for the six months ended August 3, 2018 are not necessarily indicative of the results to be expected for the entire year ending February 1, 2019.

SELECTED HISTORICAL CONSOLIDATED FINANCIAL DATA OF ENGILITY

The following tables set forth selected consolidated financial information for Engility. The selected statement of operations data for the nine months ended September 28, 2018 and September 29, 2017 and the selected balance sheet data as of September 28, 2018 and September 29, 2017 have been derived from Engility’s unaudited consolidated financial statements. In the opinion of Engility’s management, all adjustments considered necessary for a fair presentation of the interim financial information have been included. The selected statement of operations data for each of the fiscal years in the three-year period ended December 31, 2017 and the selected balance sheet data for each corresponding fiscal year have been derived from Engility’s consolidated financial statements that were audited by PricewaterhouseCoopers LLP. The selected statement of operations data for each of the fiscal years in the two-year period ended December 31, 2014 and the selected balance sheet data for each corresponding fiscal year have been derived from Engility’s consolidated financial statements that have been subsequently updated to reflect the retrospective adoption of Accounting Standards Update 2015-03, for which an updated audit report has not been issued. The following information should be read together with Engility’s consolidated financial statements, the notes related thereto and management’s related reports on Engility’s financial condition and performance, all of which are contained in Engility’s Annual Report on Form 10-K for the year ended December 31, 2017 and in subsequent reports filed with the SEC, which are incorporated herein by reference. See “Where You Can Find More Information” on page 156 of this joint proxy statement/prospectus. The operating results for the nine months ended September 28, 2018 are not necessarily indicative of the results to be expected for the entire fiscal year ending December 31, 2018.

SUMMARY UNAUDITED PRO FORMA CONDENSED COMBINED FINANCIAL INFORMATION

The following table shows summary unaudited pro forma condensed combined financial information about the combined financial condition and operating results of SAIC and Engility after giving effect to the merger. The unaudited pro forma financial information assumes that the merger is accounted for by applying the acquisition method with SAIC treated as the acquirer. The unaudited pro forma condensed combined balance sheet data gives effect to the merger as if it had occurred on August 3, 2018. The unaudited pro forma condensed combined statement of income data gives effect to the merger as if it had occurred on February 4, 2017. The summary unaudited selected pro forma condensed combined financial information listed below has been derived from and should be read in conjunction with (i) the more detailed unaudited pro forma condensed combined financial information, including the notes thereto, appearing elsewhere in this joint proxy statement/prospectus and (ii) the consolidated financial statements and the related notes of both SAIC and Engility, each incorporated herein by reference. See “Unaudited Pro Forma Condensed, Consolidated and Combined Financial Information” on page 128 and “Where You Can Find More Information” on page 156 of this proxy statement/prospectus.

SAIC and Engility have different fiscal years. SAIC utilizes a 52/53 week fiscal year ending on the Friday closest to January 31, with fiscal quarters typically consisting of 13 weeks. SAIC’s fiscal year 2018 began on February 4, 2017 and ended on February 2, 2018, with its first six months in the current fiscal year ending on August 3, 2018. Engility’s fiscal year begins on January 1 and ends on December 31 each year, with its first six months in the current fiscal year ending on June 29, 2018. The unaudited pro forma condensed combined balance sheet and statements of income have been prepared utilizing period ends that differ by less than 93 days, as permitted by Rule 11-02 Regulation S-X.

The unaudited pro forma condensed combined financial information is presented for illustrative purposes only and is not necessarily indicative of the combined operating results or financial position that would have occurred if such transactions had been consummated on the dates and in accordance with the assumptions described herein, nor is it necessarily indicative of the combined company’s future operating results or financial position. In addition, as explained in more detail in the accompanying notes to the unaudited pro forma condensed combined financial information, the preliminary allocation of the pro forma aggregate consideration reflected in the unaudited pro forma condensed combined financial information is subject to adjustment and may vary materially from the definitive allocation of the final aggregate consideration that will be recorded subsequent to completion of the merger. The determination of the final aggregate consideration will be based on the number of shares of Engility common stock outstanding and SAIC’s stock price at closing. For additional information on the limitations of this information, see “Risk Factors—Risk Factors Relating to SAIC Following the Merger—Other Risks—The historical and unaudited pro forma condensed combined financial information included elsewhere in this joint proxy statement/prospectus may not be representative of SAIC’s results after the merger, and accordingly, you have limited financial information on which to evaluate the combined company” on page 31 of this proxy statement/prospectus.

Unaudited Equivalent and Comparative Per Share Data

The following table sets forth, for the six months ended August 3, 2018 and the fiscal year ended February 2, 2018, selected per share information for SAIC common stock on a historical and unaudited pro forma combined basis. The table also sets forth, for the six months ended June 29, 2018 and the fiscal year ended December 31, 2017, selected per share information for Engility common stock on a historical and pro forma equivalent basis. As SAIC is the accounting acquiror and has not yet reported results for the third quarter of its fiscal year 2019, the pro forma information below does not reflect the third quarter results of either company. Except for the historical information as of and for the year ended February 2, 2018 (for SAIC) and December 31, 2017 (for Engility), the information in the table is unaudited. You should read the table below together with the historical consolidated financial statements and related notes of SAIC and Engility contained in their respective Annual Reports on Form 10-K for the year ended February 2, 2018 (for SAIC) and December 31, 2017 (for Engility) and Quarterly Reports on Form 10-Q for the quarters ended May 4, 2018 and August 3, 2018 (for SAIC) and March 30, 2018 and June 29, 2018 (for Engility), all of which are incorporated by reference into this joint proxy statement/prospectus. See “Where You Can Find More Information” on page 156.

The SAIC pro forma combined earnings per share were calculated using the methodology described below under the heading “Unaudited Pro Forma Condensed Combined Financial Information,” and is subject to all the assumptions, adjustments and limitations described thereunder. The SAIC pro forma combined cash dividends per common share represent SAIC’s historical cash dividends per common share. The SAIC pro forma combined book value per share was calculated by dividing total combined SAIC and Engility common stockholders’ equity by pro forma equivalent common shares. The Engility pro forma equivalent per common share amounts were calculated by multiplying the SAIC pro forma combined per share information by the exchange ratio of 0.450.

CAUTIONARY STATEMENT REGARDING FORWARD-LOOKING STATEMENTS

This joint proxy statement/prospectus and the documents incorporated by reference into this joint proxy statement/prospectus contain certain forecasts and other forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995 with respect to the financial condition, results of operations, business strategies, operating efficiencies or synergies, revenue enhancements, competitive positions, growth opportunities, plans and objectives of the management of each of SAIC, Engility and, following the merger, the combined company, the merger and the markets for SAIC and Engility common stock and various other matters. Statements in this joint proxy statement/prospectus and the documents incorporated by reference herein that are not historical facts are hereby identified as “forward-looking statements” for the purpose of the safe harbor provided by Section 21E of the Exchange Act, and Section 27A of the Securities Act. These forward-looking statements, including, without limitation, those regarding the expected timing and benefits of the proposed transaction, such as efficiencies, cost savings, enhanced revenues, growth potential, market profile and financial strength, and the competitive ability and position of the combined company, and other statements identified by words such as “will,” “estimates,” “anticipates,” “believes,” “expects,” “projects,” “plans,” “intends,” “may,” “should,” “could,” “seeks” and similar expressions, are subject to a number of risks, uncertainties and assumptions, many of which are beyond our control. These forward-looking statements are based upon the judgment and assumptions of SAIC and Engility or, following the merger, the combined company as of the date of such statements concerning future developments and events, many of which are beyond their control. These forward-looking statements, and the assumptions upon which they are based, (i) are not guarantees of future results, (ii) are inherently speculative and (iii) are subject to a number of risks and uncertainties. Actual events and results may differ materially from those anticipated, estimated, projected or implied in those statements if one or more of these risks or uncertainties materialize, or if underlying assumptions prove incorrect.

Forward-looking statements are found at various places throughout this joint proxy statement/prospectus, including in the sections entitled “The Merger and the Stock Issuance—Certain Forecasts Prepared by SAIC,” “The Merger and the Stock Issuance—Certain Forecasts Prepared by Engility” and “Risk Factors.” Important factors that could cause actual results to differ materially from those indicated by such forward-looking statements include those set forth in SAIC’s and Engility’s filings with the SEC, including their respective Annual Reports on Form 10-K for the years ended February 2, 2018 and December 31, 2017, as updated by subsequent Quarterly Reports on Form 10-Q. These important factors also include those set forth under “Risk Factors” in this joint proxy statement/prospectus as well as, among others, risks and uncertainties relating to:

Due to these risks and uncertainties, there can be no assurance that the proposed merger or any other transaction described herein will in fact be completed in the manner described or at all. You should be aware that new factors may emerge from time to time and it is not possible for SAIC or Engility to identify all such factors nor can SAIC or Engility predict the impact of each such factor on the proposed transaction or the combined company. You should not place undue reliance on these forward-looking statements, which speak only as of the date of this document. Unless legally required, SAIC and Engility undertake no obligation and each expressly disclaim any such obligation, to update publicly any forward-looking statements, whether as a result of new information, future events, changed circumstances or otherwise. Furthermore, any information about the intentions of SAIC, Engility or, following the merger, the combined company contained in any of their respective forward-looking statements reflect their intentions as of the date of such forward-looking statements, and are based upon, among other things, existing regulatory, technological, industry, competitive, economic and market conditions, and their assumptions as of such date. SAIC, Engility or, following the merger, the combined company may change their intentions, strategies or plans at any time and without notice, based upon any changes in such factors or assumptions or otherwise.

Prospective Financial Information

The prospective financial information included in this document was not prepared with a view toward public dissemination or compliance with published guidelines of the SEC or the guidelines established by the American Institute of Certified Public Accountants for preparation or presentation of prospective financial information. The prospective financial information included in this document has been prepared by, and is the responsibility of, SAIC’s and Engility’s management, as applicable.

Deloitte & Touche LLP has not audited, reviewed, examined, compiled nor applied agreed-upon procedures with respect to the accompanying prospective financial information and, accordingly, does not express an opinion or any other form of assurance on such information or its achievability, and assumes no responsibility for, and disclaims any association with, the prospective financial information. The Deloitte & Touche LLP report incorporated by reference in this joint proxy statement/prospectus relates only to the previously issued financial statements of SAIC. It does not extend to the prospective financial information and should not be read to do so.

PricewaterhouseCoopers LLP has not audited, reviewed, examined, compiled nor applied agreed-upon procedures with respect to the accompanying prospective financial information and, accordingly, PricewaterhouseCoopers LLP does not express an opinion or any other form of assurance with respect thereto. The PricewaterhouseCoopers LLP report incorporated by reference in this joint proxy statement/prospectus relates only to the previously issued financial statements of Engility. It does not extend to the prospective financial information and should not be read to do so.

RISK FACTORS

In addition to the other information included and incorporated by reference into this joint proxy statement/prospectus, including the matters addressed in the section entitled “Cautionary Statement Regarding Forward-Looking Statements,” you should carefully consider the following risks before deciding whether to vote for the adoption and approval of the merger agreement, in the case of Engility stockholders, or for the issuance of shares of SAIC common stock in connection with the merger, in the case of SAIC stockholders. In addition, you should read and consider the risks associated with each of the businesses of SAIC and Engility because these risks will also affect the combined company. These risks can be found in SAIC’s and Engility respective Annual Reports on Form 10-K for fiscal years ended February 2, 2018, and December 31, 2017, respectively, both of which are filed with the SEC and incorporated by reference into this joint proxy statement/prospectus. You should also read and consider the other information in this joint proxy statement/prospectus and the other documents incorporated by reference into this joint proxy statement/prospectus. See the section entitled “Where You Can Find More Information,” beginning on page 156.

Risk Factors Relating to the Merger

The exchange ratio and the amount of the cash consideration are fixed and will not be adjusted in the event of any change in either SAIC’s or Engility’s stock price.

Upon the closing of the merger, each share of Engility common stock will be converted into the right to receive 0.450 of a share of SAIC common stock. The exchange ratio was fixed in the merger agreement and will not be adjusted for changes in the market price of either SAIC common stock or Engility common stock. Changes in the price of SAIC common stock prior to the merger will affect the market value of the merger consideration that Engility stockholders will receive on the date of the merger. Stock price changes may result from a variety of factors (many of which are beyond our control), including the following factors:

Under the merger agreement, there will be no adjustment to the per share merger consideration for changes in the market price of either shares of SAIC common stock or shares of Engility common stock, and neither company is permitted to terminate the merger agreement or resolicit the vote of SAIC stockholders or Engility stockholders solely because of changes in the market prices of either company’s stock. We encourage you to obtain current market quotations for shares of SAIC common stock and for shares of Engility common stock before voting.

Because the merger will be completed after the date of the special meetings, at the time of your special meeting, you will not know the exact market value of the SAIC common stock that Engility stockholders will receive upon completion of the merger. You should consider the following two risks:

special meeting, respectively. Therefore, while the number of SAIC common shares to be issued per Engility common share is fixed, SAIC stockholders cannot be sure that the market value of the consideration that will be paid to Engility stockholders upon completion of the merger will not increase.

Failure to complete the merger could negatively affect the stock prices and the future business and financial results of SAIC and Engility.

If the merger is not completed, the ongoing businesses of Engility or SAIC may be adversely affected and SAIC and Engility will be subject to several risks, including the following:

In addition, if the merger is not completed, SAIC or Engility could be subject to litigation related to any failure to complete the merger or to perform their respective obligations under the merger agreement.

If the merger is not completed, SAIC and Engility cannot assure their stockholders that these risks will not materialize and will not materially affect the business, financial results and stock prices of SAIC or Engility.

The merger agreement contains provisions that could discourage a potential competing acquirer of either Engility or SAIC or could result in any competing proposal being at a lower price than it might otherwise be.

The merger agreement contains “no-shop” provisions that, subject to limited exceptions, restrict Engility and SAIC’s ability to solicit, encourage, facilitate or discuss competing third-party proposals to acquire all or a significant part of Engility or SAIC. In addition, the other party generally has an opportunity to offer to modify the terms of the proposed merger in response to any competing acquisition proposals

that may be made before such board of directors may withdraw or qualify its recommendation regarding the proposals described herein. In some circumstances on termination of the merger agreement, one of the parties may be required to pay a termination fee or expenses to the other party. See “The Merger Agreement—No Solicitation of Alternative Proposals,” “The Merger Agreement—Termination of the Merger Agreement” and “The Merger Agreement—Termination Fees and Expenses; Liability for Breach.”

These provisions could discourage a potential competing acquirer that might have an interest in acquiring all or a significant part of Engility or SAIC from considering or proposing that acquisition, even if it were prepared to pay consideration with a higher value than that market value proposed to be received or realized in the merger, or might result in a potential competing acquirer proposing to pay a lower price than it might otherwise have proposed to pay because of the added expense of the termination fee or expenses that may become payable in certain circumstances.

If the merger agreement is terminated and either SAIC or Engility attempts to seek another business merger, SAIC or Engility, as applicable, may not be able to negotiate a transaction with another party on terms comparable or better than the terms of the merger.

The pendency of the merger could adversely affect the business and operations of SAIC and Engility.

In connection with the merger, some customers or vendors of each of SAIC and Engility may delay or defer decisions or reduce their level of business with either or both of the companies, any of which could negatively affect the revenues, earnings, cash flows and expenses of SAIC and Engility, regardless of whether the merger is completed. Similarly, current and prospective employees of SAIC and Engility may experience uncertainty about their future roles with the combined company following the merger, which may materially adversely affect the ability of each of SAIC and Engility to attract and retain key management, sales, marketing, operational and technical personnel during the pendency of the merger. In addition, due to operating covenants in the merger agreement, each of SAIC and Engility may be unable, during the pendency of the merger, to pursue strategic transactions, undertake significant capital projects, undertake certain significant financing transactions and otherwise pursue other actions that are not in the ordinary course of business, even if such actions would prove beneficial. Any of these effects could adversely affect the ability to generate revenue at anticipated levels prior to the completion of the merger. Moreover, the pursuit of the merger and the preparation for the integration of the companies may place a significant burden on the management and personnel of both companies. The diversion of management’s attention away from operating the companies in the ordinary course could adversely affect SAIC’s and Engility financial results.

Current SAIC stockholders and Engility stockholders will have a reduced ownership and voting interest in the combined company after the merger.

SAIC expects to issue or reserve for issuance approximately 17,293,723 shares of SAIC common stock to Engility stockholders in connection with the merger (including shares of SAIC common stock to be issued in connection with outstanding Engility equity awards). Based on the number of shares of common stock of SAIC and Engility outstanding on November 29, 2018, the record date for the two companies’ special meetings of stockholders, and the relative stock prices of SAIC and Engility on such date, upon the completion of the merger, current SAIC stockholders and former Engility stockholders are expected to own approximately 72% and 28% of the common stock of SAIC, respectively.

SAIC stockholders and Engility stockholders currently have the right to vote for their respective directors and on other matters affecting their company. If and when the merger occurs, each Engility stockholder who receives shares of SAIC common stock will become a stockholder of SAIC with a percentage ownership of the combined company that will be smaller than the stockholder’s percentage ownership of Engility (without considering such stockholder’s current ownership of SAIC shares). Correspondingly, each SAIC stockholder will remain a stockholder of SAIC with a percentage ownership of the combined company that will be smaller than the stockholder’s percentage of SAIC prior to the merger (without considering such stockholder’s current ownership of Engility shares). As a result of these potentially reduced ownership percentages, SAIC stockholders will have less voting power in the combined company than they now have with respect to SAIC, and former Engility stockholders will have less voting power in the combined company than they now have with respect to Engility.

The shares of SAIC common stock to be received by Engility stockholders upon completion of the merger will have different rights from Engility common shares.

Upon completion of the merger, Engility stockholders will no longer be stockholders of Engility, but will instead become stockholders of SAIC, and their rights as SAIC stockholders will be governed by the terms of SAIC’s amended and restated certificate of incorporation, as it may be amended from time to time, which is referred to in this joint proxy statement/prospectus as SAIC’s certificate of incorporation, and SAIC’s amended and restated by-laws, as they may be amended from time to time, which are referred to in this joint proxy statement/prospectus as SAIC’s by-laws. The terms of SAIC’s certificate of incorporation and SAIC’s by-laws are in some respects materially different than the terms of Engility’s amended and restated certificate of incorporation, as it may be amended from time to time, which is referred to in this joint proxy statement/prospectus as Engility’s certificate of incorporation, and Engility’s amended and restated by-laws, as they may be amended from time to time, which are referred to in this joint proxy statement/prospectus as Engility’s by-laws, which currently govern the rights of Engility stockholders. See “Comparison of Rights of Engility Stockholder and SAIC Stockholders” beginning on page 143 of this joint proxy statement/prospectus for a discussion of the different rights associated with Engility common shares and shares of SAIC common stock.

The market price of shares of SAIC common stock may be affected by factors different from those that historically have affected shares of Engility common stock and will continue to fluctuate after the merger.

Upon completion of the merger, holders of Engility common stock will become holders of SAIC common stock. The businesses of SAIC differ from those of Engility in certain respects, and, accordingly, the financial position or results of operations and/or cash flows of SAIC after the merger, as well as the market price of shares of SAIC common stock, may be affected by factors different from those currently affecting the financial position or results of operations and/or cash flows of Engility. In addition, the stock market has experienced significant price and volume fluctuations in recent times which, if they continue to occur, could have a material adverse effect on the market for, or liquidity of, the SAIC common stock, regardless of SAIC’s actual operating performance. As a result, the market price of shares of SAIC common stock may fluctuate significantly following completion of the merger, and holders of Engility common stock could lose some or all of the value of their investment in SAIC common stock.

Directors and executive officers of SAIC and Engility have financial interests in the merger that may be different from, or in addition to, those of other SAIC stockholders and Engility stockholders, which could have influenced their decisions to support or approve the merger.

In considering whether to approve the proposals at the special meetings, SAIC and Engility stockholders should recognize that directors and executive officers of SAIC and Engility have interests in the merger that may differ from, or that are in addition to, their interests as stockholders of SAIC and stockholders of Engility. The SAIC Board and the Engility Board were aware of these interests at the time each approved the merger agreement. These interests may cause SAIC’s and Engility directors and executive officers to view the merger differently than you may view it as a stockholder. See “The Merger and the Stock Issuance—Financial Interests of SAIC Directors and Executive Officers in the Merger” and “The Merger and the Stock Issuance—Financial Interests of Engility Directors and Executive Officers in the Merger.”

Financing of the merger is not assured.

Subsequent to entering into the merger agreement, SAIC entered into an amended and restated credit agreement with Citibank, N.A. pursuant to which Citibank, N.A. and certain other lenders have committed to provide it with a new secured $1.068 billion term loan A maturing on October 31, 2023. The proceeds of this new term loan A are necessary to enable SAIC to repay Engility’s existing credit facility and outstanding notes. Citibank, N.A.’s obligation to provide the term loan A, however, is subject to specified limited conditions, and SAIC cannot assure you that these conditions will be met. The closing of the merger is not conditioned on SAIC’s ability to obtain financing. If SAIC is unable to obtain the term loan A pursuant to the terms of the amended and restated credit agreement or otherwise, SAIC still could be required to close the merger resulting in a default under its and Engility’s existing credit agreements, or

SAIC could be subject to claims under the merger agreement, each of which could have a material adverse effect on SAIC’s business. See “The Merger and the Stock Issuance—Financing Related to the Merger.”

The opinions obtained by the boards of SAIC and Engility from their respective financial advisors do not and will not reflect changes in circumstances after the date of such opinions.

The SAIC Board received written opinions dated September 9, 2018 from Citigroup Global Markets Inc. and Stone Key, its financial advisors, that the merger consideration to be paid by SAIC was fair, from a financial point of view, to SAIC, as of such date, and based on and subject to the qualifications, limitations and assumptions set forth in such opinion, and, in addition, the Engility Board received a written opinion dated September 9, 2018 from Guggenheim Securities, its financial advisor, that the merger consideration to be paid to Engility stockholders was fair, from a financial point of view, to such stockholders, as of such date, subject to the assumptions, limitations, qualifications and other conditions contained in such opinion, and based on economic, capital markets and other conditions, and the information made available to Guggenheim Securities, as of the date of such opinion. Changes in the operations or prospects of SAIC or Engility, general market and economic conditions and other factors that may be beyond the control of SAIC and Engility, and on which the above-described opinions were based, may alter the value of SAIC or Engility or the prices of shares of SAIC common stock or Engility common stock by the time the merger is completed. SAIC and Engility have not obtained, and do not expect to request, updated opinions from their respective financial advisors. None of the above-listed opinions speak to any date other than the date of such opinion. For a more complete description of the above-described opinions, please refer to “The Merger and the Stock Issuance—Opinions of SAIC’s Financial Advisors” and “The Merger and the Stock Issuance—Opinions of Engility’s Financial Advisors.”

Due to the merger, the ability of the combined company to use net operating losses to offset future taxable income may be restricted and these net operating losses could expire or otherwise be unavailable.

As of December 31, 2017, Engility had federal net operating loss carryforwards, or “NOLs”, of approximately $436 million and approximately $421 million of state NOLs. In general, under Section 382 of the Code, a corporation that undergoes an “ownership change” is subject to limitations on its ability to utilize its NOLs to offset future taxable income. If the merger is completed, Engility’s existing NOLs may be subject to limitations and SAIC may not be able to fully use these NOLs to offset future taxable income. In addition, if SAIC undergoes any subsequent ownership change, its ability to utilize NOLs could be further limited.

If the merger does not qualify as a “reorganization” for U.S. federal income tax purposes, U.S. holders will be required to recognize gain or loss for U.S. federal income tax purposes at the time of the exchange of their Engility common stock for the merger consideration in the merger.

The U.S. federal income tax consequences of the merger to U.S. holders (as defined under the heading “Material U.S. Federal Income Tax Consequences”) will depend on whether the merger qualifies as a “reorganization” for U.S. federal income tax purposes.

As further described in the section entitled “The Merger Agreement—Conditions to Completion of the Merger”, Engility’s obligation to effect the merger is subject to the satisfaction, or waiver by Engility, at or prior to the effective time of the merger, of the condition that Engility receive a written tax opinion from Weil, Gotshal & Manges LLP, legal counsel to Engility, dated as of the closing date of the merger, to the effect that the merger will qualify as a “reorganization” within the meaning of Section 368(a) of the Code. In the event that Weil, Gotshal & Manges LLP does not render such tax opinion, and Engility does not otherwise waive this condition, the condition may be satisfied if Morrison & Foerster LLP, legal counsel to SAIC, renders such tax opinion.

There can be no assurance, that the Internal Revenue Service (the “IRS”) will not take a contrary position to views expressed herein or that a court will not agree with a contrary position of the IRS. If, contrary to the opinion, the merger fails to qualify as a reorganization or if any requirement for the merger to qualify as a “reorganization” within the meaning of Section 368(a) of the Code is not satisfied, a U.S. holder of Engility common stock generally would recognize gain or loss for U.S. federal income tax

purposes on each share of Engility common stock surrendered in the merger in an amount equal to the difference between (1) the fair market value of the merger consideration received in exchange for such surrendered share upon completion of the merger and (2) the holder’s basis in the share of Engility common stock surrendered. Any gain or loss recognized generally would be long-term capital gain or loss if the U.S. holder’s holding period in a particular block of Engility common stock exceeds one year at the effective time. Long-term capital gain of non-corporate U.S. holders (including individuals) generally is taxed at reduced U.S. federal income tax rates. The deductibility of capital losses is subject to limitations. For a more complete discussion of the material U.S. federal income tax consequences of the merger, please carefully review the information set forth in the section entitled “Material U.S. Federal Income Tax Consequences”.

Risk Factors Relating to SAIC Following the Merger

Operational Risks

SAIC expects to incur substantial expenses related to the merger.

SAIC expects to incur substantial expenses in connection with completing the merger and integrating the business, operations, networks, systems, technologies, policies and procedures of Engility with those of SAIC. There are a large number of systems that will likely be integrated, including management information, purchasing, accounting and finance, sales, payroll and benefits, fixed asset, lease administration and regulatory compliance. While SAIC has assumed that a certain level of transaction and integration expenses would be incurred, there are a number of factors beyond its control that could affect the total amount or the timing of its integration expenses. Many of the expenses that will be incurred, by their nature, are difficult to estimate accurately at the present time. Due to these factors, the transaction and integration expenses associated with the merger are likely in the near term to significantly reduce the savings that SAIC expects to achieve from the elimination of duplicative expenses and the realization of economies of scale and cost savings related to the integration of the businesses following the completion of the merger.

Following the merger, the combined company may be unable to integrate successfully the businesses of SAIC and Engility and realize the anticipated benefits of the merger.

The proposed transaction involves the merger of two companies which currently operate as independent public companies. The combined company will be required to devote significant management attention and resources to integrating the business practices and operations of SAIC and Engility. Potential difficulties the combined company may encounter in the integration process include the following:

For all these reasons, you should be aware that it is possible that the integration process could result in the distraction of the combined company’s management, the disruption of the combined company’s ongoing business or inconsistencies in the combined company’s products, services, standards, controls, procedures and policies, any of which could adversely affect the ability of the combined company to maintain relationships with customers, vendors and employees or to achieve the anticipated benefits of the merger, or could otherwise adversely affect the business and financial results of the combined company.

Other Risks

Our existing credit agreement and the other agreements that will govern the indebtedness to be incurred by SAIC in connection with the merger contain provisions that impose restrictions on the ability of SAIC and certain of its subsidiaries to operate their businesses. These provisions include pledges of collateral, affiliate guarantees and various affirmative and negative covenants that, subject to certain significant exceptions, restrict the ability of SAIC and certain of its subsidiaries to, among other things, have liens on their property, incur additional indebtedness, enter into sale and lease-back transactions, make loans, advances or other investments, make non-ordinary course asset sales, declare or pay dividends or make other distributions with respect to equity interests, merge or consolidate with any other person or sell or convey certain of its assets to any one person, among various other things. The ability of SAIC and its subsidiaries to comply with certain of these provisions may be affected by events beyond their control. Failure to comply with these covenants could result in an event of default, which, if not cured or waived, would permit SAIC’s lenders to accelerate SAIC’s debt repayment obligations and take other actions with respect to SAIC’s and its subsidiaries’ assets that serve as collateral for such obligations. In addition, our existing credit agreement has a cross-default provision. If a default occurs under certain debt instruments, such default may cause a default under our existing credit agreement and have a wider impact on liquidity than might otherwise arise from a default of such single debt instrument

The historical and unaudited pro forma condensed combined financial information included elsewhere in this joint proxy statement/prospectus may not be representative of SAIC’s results after the merger, and accordingly, you have limited financial information on which to evaluate the combined company.

SAIC and Engility will continue to operate as separate companies prior to the merger. SAIC and Engility have no prior history as a combined company. The historical financial statements of Engility may be different from those that would have resulted had Engility been operated as part of SAIC. The pro forma condensed combined financial information appearing elsewhere herein has been presented for informational purposes only and is not necessarily indicative of the financial position or results of operations that actually would have occurred had the merger been completed as of the dates indicated, nor is it indicative of the future operating results or financial position of the combined company. The unaudited pro forma condensed combined financial information reflects adjustments, which are based upon preliminary estimates, to allocate the aggregate consideration to Engility assets and liabilities. The aggregate consideration allocation reflected in the pro forma condensed combined financial information included in this joint proxy statement/prospectus is preliminary, and the final allocation of the aggregate consideration will be based upon the actual aggregate consideration and the fair value of the assets and liabilities of Engility as of the date of the completion of the merger. The unaudited pro forma condensed combined financial information does not (i) reflect future events that may occur after the merger, including the incurrence of costs related to the planned integration of Engility, any future non-recurring charges resulting from the merger and any termination of contracts by customers as a direct result of the merger, and (ii) consider potential effects of future market conditions on revenues or expense efficiencies. The unaudited pro forma financial information presented in this joint proxy statement/prospectus is based in part on certain assumptions regarding the merger that SAIC believes are reasonable under the circumstances. SAIC cannot assure you that the assumptions will prove to be accurate over time.

If SAIC’s goodwill or other intangible assets become impaired, it may be required to record a significant charge to earnings and reduce its stockholders’ equity.

As of August 3, 2018, a significant portion of SAIC’s total consolidated assets reflected on the consolidated balance sheet incorporated by reference into this joint proxy/prospectus consisted of goodwill and intangible assets. Consummation of the merger is expected to result in SAIC recognizing additional goodwill and intangible assets on its consolidated balance sheet. See “Accounting Treatment.” Intangible assets with finite lives will be amortized using the method that best reflects how their economic benefits are utilized or, if a pattern of economic benefits cannot be reliably determined, on a straight-line basis over their estimated useful lives. Goodwill and intangible assets with indefinite lives will not be amortized, but instead tested for potential impairment annually. Intangible assets and goodwill will be assessed for impairment whenever events or changes in circumstances indicate that the carrying value may not be recoverable. If SAIC’s goodwill or other intangible assets are determined to be impaired in the future, it may be required to record additional significant, non-cash charges to earnings during the period in which the impairment is determined to have occurred.

The SAIC and Engility prospective financial information is inherently subject to uncertainties.

While presented with numeric specificity, the SAIC and Engility prospective financial information provided in this document was prepared based on numerous variables and assumptions (including, but not limited to, those related to industry performance and competition and general business, economic, market and financial conditions and additional matters specific to SAIC or Engility business, as applicable) that are inherently subjective and uncertain and are largely beyond the control of the respective management of each. As a result, actual results may differ from the prospective financial information. Important factors that may affect actual results and cause these projected financial forecasts to not be achieved include, but are not limited to, risks and uncertainties relating to SAIC’s or Engility’s business, as applicable (including each company’s ability to achieve strategic goals, objectives and targets over applicable periods) and general industry, business, competitive, technological and economic conditions. For more information see the sections entitled “The Merger and the Stock Issuance—Certain Forecasts Prepared by SAIC” beginning on page 88 and “The Merger and the Stock Issuance—Certain Forecasts Prepared by Engility” beginning on page 92.

SAIC and Engility may be targets of securities class action and derivative lawsuits which could result in substantial costs and may delay or prevent the merger from being completed.

As further discussed in the section entitled “Litigation Related to the Merger” beginning on page 98 of this joint proxy statement/prospectus, four lawsuits related to the merger have been filed by SAIC and Engility stockholders, three of which are purported class actions. Securities class action lawsuits and derivative lawsuits are often brought against public companies that have entered into merger agreements. While the defendants believe that these lawsuits are without merit, defending against the claims could result in substantial costs and divert management time and resources. In addition, the existence of litigation related to the merger could affect the likelihood of obtaining the required approval from SAIC or Engility stockholders. Moreover, an adverse judgment in these or any additional lawsuits could result in monetary damages, which could have a negative impact on SAIC’s and Engility’s respective liquidity and financial condition. Additionally, if a plaintiff is successful in obtaining an injunction prohibiting completion of the merger, then that injunction may delay or prevent the merger from being completed, which may adversely affect SAIC’s and Engility’s respective business, financial position and results of operations.

Other Risk Factors of SAIC and Engility

SAIC’s and Engility businesses are, and will continue to be, subject to the risks described above. In addition, SAIC and Engility are, and will continue to be, subject to the risks described in SAIC’s and Engility’s Annual Reports on Form 10-K for the fiscal years ended February 2, 2018, and December 31, 2017, respectively, as amended and as updated by subsequent Quarterly Reports on Form 10-Q, all of which are filed with the SEC and incorporated by reference into this joint proxy statement/prospectus. See “Where You Can Find More Information” beginning on page 156 for the location of information incorporated by reference in this joint proxy statement/prospectus.

THE COMPANIES

SAIC

Science Applications International Corporation
12010 Sunset Hills Road
Reston, VA 20190
(703) 676-4300

SAIC is a leading provider of technical, engineering and enterprise information technology (IT) services primarily to the U.S. government. SAIC provides engineering, systems integration and information technology offerings for large, complex government projects and offer a broad range of services with a targeted emphasis on higher-end, differentiated technology services. SAIC’s end-to-end enterprise IT offerings span the entire spectrum of its customers' IT infrastructure. SAIC commenced operations on September 27, 2013 following completion of a spin-off transaction from its former parent, Leidos Holdings, Inc. In May 2015 SAIC completed the acquisition of privately held Scitor Holdings, Inc., a leading provider of services to the intelligence community, which enabled SAIC to gain sufficient scale to competitively pursue opportunities within the intelligence community.

SAIC’s business has a long and successful history, tracing its roots to the earliest days of its former parent, Leidos Holdings, Inc., which was founded in 1969 as a scientific research and engineering firm. The U.S. federal government agencies SAIC serves include all branches of the U.S. military (Army, Air Force, Navy, Marines and Coast Guard), U.S. Defense Logistics Agency, National Aeronautics and Space Administration (NASA), U.S. Department of State, and U.S. Department of Homeland Security (DHS). SAIC’s long-standing customer relationships have enabled it to achieve an in-depth understanding of its customers’ missions and provide differentiated service offerings to meet its customers’ most complex requirements. SAIC’s offerings include: engineering; technology and equipment platform integration; maintenance of ground and maritime systems; logistics; training and simulation; operation and program support services; and end-to-end services spanning the design, development, integration, deployment, management and operations, sustainment and security of its customers’ entire IT infrastructure. SAIC serves its customers through approximately 1,300 active contracts and task orders. SAIC has more than 15,000 individuals that are led by an experienced executive team of proven industry leaders. Substantially all of our revenues and tangible long-lived assets are generated by or owned by entities located in the United States.

SAIC’s core strengths have supported its successful performance on programs of national importance. Those strengths include:

Enduring Customer Relationships and Mission-Orientation. SAIC has strong and long-lasting customer relationships throughout the U.S. government. Its track record of serving the missions of its government customer spans decades, including several enduring customer relationships that have lasted 20 years or more. SAIC’s employees, many of whom are deployed at customer sites, work closely with its customers in fulfilling their missions. SAIC’s strong customer relationships enable it to develop deep customer knowledge and translate its mission understanding into successful program execution that fosters continued demand for its services.

Full Life Cycle Offerings. SAIC integrates technologies and delivers services that provide its customers with seamless end-to-end solutions. SAIC’s expertise includes initial requirements definition, development and integration services, training, logistics and sustainment. These full life cycle offerings, combined with deep customer knowledge, allow SAIC to more effectively support its customers’ missions.

Significant Scale and Diversified Contract Base. With approximately $4.5 billion in revenue in fiscal 2018, SAIC is one of the largest pure-play technical service providers to the U.S. government. SAIC’s significant scale advantage enables it to serve as a prime systems integrator on large, complex programs and to allocate resources toward further developing and expanding its repeatable, proven solutions and differentiated technical capabilities. SAIC’s diversified revenue base consists of programs ranging from research and development to operations and maintenance.

Technical Experts Led by Experienced Management. The quality, training and knowledge of SAIC’s employees are important competitive assets. SAIC’s skilled workforce ranges from entry-level technicians to expert-level professionals in network engineering, software design and development, logistics, technology integration and systems engineering. Additionally, the majority of SAIC’s workforce holds an active security clearance, which is required on many of its existing programs and future program opportunities.

SAIC’s workforce is led by a talented and experienced senior leadership team with a long history of solving its customers’ most difficult challenges. Collectively, SAIC’s executive team averages more than 25 years of industry experience, consisting of members who have served as senior leaders in public companies and are recognized as leaders in their respective markets by customers and partners.

Repeatable Methodologies and Certified Processes. SAIC’s technical excellence is driven by its proven, repeatable, disciplined processes for management, engineering, technical support and services. SAIC deploys its tools and processes enterprise-wide and emphasize a consistent approach to planning, designing, and delivering solutions and services to its customers. SAIC holds certifications from the International Organization for Standardization (including ISO 9001:2015, ISO/IEC 27001:2013, ISO 20000-1:2011 and AS9100), and from the Capability Maturity Model Integration Institute as a CMMI®-DEV Maturity Level 3 organization and CMMI®-SVC Maturity Level 2 for Army Programs with Strategic Goals for Best Practice Service Delivery.

SAIC is organized as a matrix comprised of three customer facing operating segments supported by three market service line organizations. The three operating segments are responsible for customer relationships, business development and program management, and delivery and execution, while the market service line organizations manage our workforce and the development of SAIC’s offerings, solutions and capabilities. Each of SAIC’s three operating segments is focused on providing comprehensive technical, engineering and enterprise IT service offerings to one or more agencies of the U.S federal government. SAIC's operating segments are aggregated into one reportable segment for financial reporting purposes.

Raptors Merger Sub, Inc.

Raptors Merger Sub, Inc.
12010 Sunset Hills Road
Reston, VA 20190
(703) 676-4300

Raptors Merger Sub, Inc., a direct wholly owned subsidiary of SAIC is a Delaware corporation formed on September 5, 2018 for the purpose of effecting the merger. Upon completion of the merger, merger sub will be merged with and into Engility with Engility surviving as a direct wholly owned subsidiary of SAIC.

Merger sub has not conducted any activities other than those incidental to its formation and the matters contemplated by the merger agreement, including the preparation of applicable regulatory filings in connection with the merger.

Engility

Engility Holdings, Inc.
4803 Stonecroft Boulevard
Chantilly, VA 20151
(703) 633-8300

Engility is a leading provider of integrated solutions and services, supporting U.S. government customers in the defense, federal civilian, intelligence and space communities. Engility offers a broad range of highly technical services, leveraging its strengths in systems engineering, cybersecurity, high performance computing, enterprise modernization, and training and mission operations to solve customers’ most difficult challenges. Engility is headquartered in Chantilly, Virginia, and maintains offices around the world.

Engility was formed as a result of its spin-off from L3 Technologies (formerly, L-3 Communications Holdings, Inc.) in July 2012. Engility has provided mission critical services to the U.S. government for more than 60 years. During the past five years, Engility completed two transformative acquisitions – Dynamics Research Corporation (DRC) in 2014 and TASC, Inc. (TASC) in 2015. These acquisitions enabled Engility to diversify its customer base and capabilities, add substantial scale to its business and increase its addressable market.

During 2017, Engility streamlined its operating structure around three business groups – Intelligence Solutions, Space and Mission Systems and Defense and Security – to improve customer intimacy, enhance employee collaboration, and drive efficiencies throughout the organization so Engility could further invest in growth-related activities. These groups serve a broad range of customers, including the U.S. Department of Defense (DoD), U.S. Department of Justice (DoJ), U.S. Department of State (DoS), Federal Aviation Administration (FAA), Department of Homeland Security (DHS), and space-related and intelligence community agencies, including the Central Intelligence Agency (CIA), the National Security Agency (NSA), the National Geospatial-Intelligence Agency (NGA), Defense Intelligence Agency (DIA), the National Reconnaissance Office (NRO), National Aeronautical and Space Administration (NASA) and U.S. Air Force Space Command (AFSPC).

Engility supports its customers with a wide range of specialized technological and mission expertise. Its portfolio of offerings are assembled around capabilities that its customers demand and require.

Systems Engineering and Integration (SE&I). Engility provides engineering and integration solutions that support its customers throughout the acquisition and sustainment lifecycle of their programs. Engility’s SE&I service offerings include engineering and technology lifecycle support, information assurance, modeling and simulation, and architecture analysis and modernization.

Cybersecurity. The U.S. government has identified cyber security as a top priority—from the DoD’s need to harden weapon systems from attacks to the Department of Homeland Security’s mission of protecting our country’s critical infrastructure. Engility modernizes and develops new systems with cyber resiliency at its core with offerings that include vulnerability assessments and penetration testing, independent test and evaluation, cybersecurity systems engineering, cyber quick reaction range capability, and cyber hunting.

High Performance Computing. Engility’s legacy of high performance computing (HPC) stretches back a quarter of a century. It collaborates with scientists, technologists and decision-makers across the Federal government, industry and academia to apply complex science to real-world challenges. Its HPC capabilities include architecture and infrastructure design, data management and analytics, integration and testing, and systems operation, optimization and sustainment.

Enterprise Modernization. Engility’s enterprise services and systems optimize operations, increase cost efficiencies and improve mission effectiveness. Its offerings include architecture analysis and modernization, I.T. services and solutions, including its recently developed Cloud ASCEND™ solution, and agile software development and integration.

Mission and Operations Support. With Engility’s expertise in mission strategy, tactics and technical execution, it provides solutions that give its customers flexibility, efficiency and effectiveness in accomplishing their critical missions, including in the following areas: artificial intelligence, its Synthetic Analyst™ solution, space launch and space flight, law enforcement, intelligence analysis, air traffic management, engineering and fabrication, and communication data exchange through our Joint Range Extender (JRE) system.

Readiness and Training. From curriculum design and development to training implementation and evaluation, Engility helps domestic and international clients prepare to meet the challenges of increasingly complex environments and missions. Its readiness and training solutions include training development, learning and knowledge management and QuickRange™, its turn-key, modular shooting range.

THE SAIC SPECIAL MEETING

Date, Time and Place

The special meeting of SAIC stockholders will be held at 12010 Sunset Hills Road, Reston, Virginia 20190, on January 11, 2019, at 9:00 a.m. local time.

Matters to be Considered

At the SAIC special meeting, SAIC stockholders will be asked to vote on:

Recommendation of the SAIC Board

The SAIC Board unanimously has determined that the merger, the merger agreement and the other transactions contemplated by the merger agreement, including the issuance of SAIC common stock to Engility stockholders in connection with the merger, are in the best interests of SAIC and the SAIC stockholders and has unanimously approved and adopted the merger agreement.

The SAIC Board unanimously recommends that the SAIC stockholders vote “FOR” the proposal to issue shares of SAIC common stock to Engility stockholders in connection with the merger.

Record Date; Stock Entitled to Vote

Only holders of record of shares of SAIC common stock at the close of business on November 29, 2018, the record date for the SAIC special meeting, will be entitled to notice of, and to vote at, the SAIC special meeting or any adjournments thereof. You may cast one vote for each share of common stock of SAIC that you owned on the record date.

On the record date, there were outstanding a total of 42,368,119 shares of SAIC common stock entitled to vote at the SAIC special meeting.

Solicitation of Proxies; Revocability of Proxies

In accordance with the merger agreement, the cost of proxy solicitation for the SAIC special meeting will be borne by SAIC, other than the expenses incurred by SAIC and Engility in connection with the filing, printing and mailing of this joint proxy statement/prospectus, half of which expenses will be borne by each of SAIC and Engility. In addition to the use of the mail, proxies may be solicited by officers and directors and regular employees of SAIC, without additional remuneration, by personal interview, telephone, facsimile or otherwise. SAIC will also request brokerage firms, nominees, custodians and fiduciaries to forward proxy materials to the beneficial owners of shares held of record on the record date and will provide customary reimbursement to such firms for the cost of forwarding these materials. SAIC has retained Georgeson LLC to assist in its solicitation of proxies and has agreed to pay them a fee of $18,000, plus reasonable expenses, for these services.

If you are a holder of record on the record date for the SAIC special meeting, you have the power to revoke your proxy at any time before your proxy is voted at the SAIC special meeting. You can revoke your proxy in one of three ways:

If you choose either of the first two methods, your notice of revocation or your new proxy must be received by SAIC’s Secretary, no later than the beginning of the SAIC special meeting. If you have voted your shares by telephone or through the Internet, you may revoke your prior telephone or Internet vote by recording a different vote using the telephone or Internet, or by signing and returning a proxy card dated as of a date that is later than your last telephone or Internet vote.

If your shares are held in street name by your broker or nominee, you should contact them to change your vote. Plan participants who wish to revoke their voting instructions must contact the applicable plan trustee and follow its procedures.

Quorum

Stockholders who hold a majority of the total voting power of SAIC common stock issued and outstanding at the close of business on the record date must be present or represented by proxy to constitute a quorum to conduct the SAIC special meeting, and stockholders holding a majority of the votes entitled to be cast with respect to the proposal to issue SAIC common stock in connection with the merger must be present or represented by proxy to constitute a quorum with respect to such proposal. All shares of SAIC common stock represented at the SAIC special meeting, including abstentions and broker non-votes (shares held by a broker or nominee that are represented at the meeting, but with respect to which the broker or nominee is not instructed by the beneficial owner of such shares to vote on the particular proposal), will be treated as present for purposes of determining the presence or absence of a quorum to conduct the SAIC special meeting, but abstentions and broker non-votes will be treated as not present for purposes of determining the presence or absence of a quorum with respect to the proposal to issue SAIC common stock in connection with the merger.

Vote Required

Under the SAIC bylaws, the issuance of SAIC common stock to Engility stockholders in connection with the merger requires approval by the affirmative vote of a majority in voting interest of the holders of SAIC common stock present in person or by proxy entitled to vote on such matter at the SAIC special meeting (provided that a quorum exists).

Approval of any proposal to adjourn the SAIC special meeting, if necessary, for the purpose of soliciting additional proxies also requires approval by the affirmative vote of a majority in voting interest of the holders of SAIC common stock present in person or by proxy entitled to vote on such matter at the SAIC special meeting (provided that a quorum exists).

Abstentions and Broker Non-Votes

If you are an SAIC stockholder, abstentions have the effect of a vote against the stock issuance proposal and, if necessary, the adjournment proposal. Broker “non-votes” have no effect on the outcome of the stock issuance proposal or any adjournment proposal. Shares of common stock represented by properly executed, timely received and unrevoked proxies will be voted in accordance with the instructions indicated thereon. In the absence of specific instructions, properly executed, timely received and unrevoked proxies will be voted “FOR” each proposal. Your failure to cast a vote will also make it more difficult to meet the quorum requirement with respect to organizing the meeting, and your failure to cast a vote or your abstention from voting will make it more difficult to meet the quorum requirement with respect to the SAIC stock issuance proposal.

Voting Power of SAIC’s Directors and Executive Officers

On the record date, less than 2% of the outstanding SAIC common shares were held by SAIC directors and executive officers and their respective affiliates. SAIC currently expects that SAIC’s directors and executive officers will vote their shares in favor of the issuance of SAIC common stock to Engility stockholders in connection with the merger.

Attending the SAIC Special Meeting

All holders of SAIC common stock, including stockholders of record and stockholders who hold shares through banks, brokers or other nominees, are invited to attend the SAIC special meeting. Stockholders of record can vote in person at the special meeting. If you plan to attend the special meeting, you must hold your shares in your own name or have a letter or an account statement issued by the record holder of your shares confirming your ownership, and you must bring a form of personal photo identification with you to be admitted. SAIC reserves the right to refuse admittance to anyone without proper proof of share ownership and without proper photo identification.

Voting of Proxies by Record Stockholders

A proxy card is enclosed for use by SAIC stockholders of record. SAIC requests that its record stockholders sign the accompanying proxy and return it promptly in the enclosed postage-paid envelope. You may also vote your shares by telephone or through the Internet. Information and applicable deadlines for voting by telephone or through the Internet are set forth on the enclosed proxy card. When the accompanying proxy is returned properly executed, the shares of SAIC common stock represented by it will be voted at the SAIC special meeting or any adjournment thereof in accordance with the instructions contained in the proxy.

If a proxy is signed and returned without an indication as to how the shares of SAIC common stock represented by the proxy are to be voted with regard to a particular proposal, the SAIC common stock represented by the proxy will be voted in favor of each such proposal. At the date hereof, SAIC management has no knowledge of any business that will be presented for consideration at the special meeting and which would be required to be set forth in this joint proxy statement/prospectus other than the matters set forth in SAIC’s accompanying Notice of Special Meeting of Stockholders. In accordance with SAIC’s bylaws and Delaware law, business transacted at the SAIC special meeting will be limited to those matters set forth in such notice. Nonetheless, if any other matter is properly presented at the SAIC special meeting for consideration, it is intended that the persons named in the enclosed proxy and acting thereunder will vote in accordance with their best judgment on such matter.

Your vote is important. Accordingly, please sign and return the enclosed proxy card whether or not you plan to attend the SAIC special meeting in person.

Participants in the SAIC Retirement Plan

Each participant in the SAIC Retirement Plan has the right to instruct Vanguard Fiduciary Trust Company, as trustee of the SAIC Retirement Plan (the “Trustee”), on a confidential basis, how to vote his or her proportionate interests in all shares of common stock held in the SAIC Retirement Plan. The Trustee will vote all shares held in the SAIC Retirement Plan for which no voting instructions are received in the same proportion as the shares for which voting instructions have been received by participants in the SAIC Retirement Plan. The Trustee’s duties with respect to voting the common stock in the SAIC Retirement Plan are governed by the fiduciary provisions of the Employee Retirement Income Security Act of 1974, as amended (“ERISA”). The fiduciary provisions of ERISA may require in certain limited circumstances that the Trustee override the votes of participants with respect to the common stock held by the Trustee.

Participants in the SAIC Stock Plans

Under the terms of SAIC’s Stock Compensation Plan, Management Stock Compensation Plan and Key Executive Stock Deferral Plan, Vanguard Fiduciary Trust Company, as trustee of these stock plans, has the power to vote the shares of common stock held in these stock plans. Vanguard will vote all those shares in the same proportion that other SAIC stockholders collectively vote their shares of common stock. If you are a participant in these stock plans, you do not have the right to instruct Vanguard how to vote or to otherwise vote your proportionate interests in the shares of common stock held in these stock plans.

Shares Held in Street Name

If you hold your shares of SAIC stock in a stock brokerage account or if your shares are held by a bank or nominee (that is, in street name), you must provide the record holder of your shares with instructions on how to vote your shares if you wish them to be counted. Please follow the voting instructions provided by your broker, bank or nominee. Please note that you may not vote shares held in street name by returning a proxy card directly to SAIC or by voting in person at the SAIC special meeting. Further, brokers who hold shares of SAIC stock on behalf of their customers may not vote those shares without specific instructions from their customers.

If you hold your SAIC stock in street name and you do not instruct your broker on how to vote any of your shares, your broker may not vote those shares. For a discussion of the consequences of such broker non-votes, see “—Abstentions and Broker Non-Votes” beginning on page 37 of this joint proxy statement/prospectus.

THE ENGILITY SPECIAL MEETING

Date, Time and Place

The special meeting of Engility stockholders will be held at 4803 Stonecroft Boulevard, Chantilly, Virginia 20151, on January 11, 2019, at 9:00 a.m. local time.

Matters to Be Considered

The purpose of the Engility special meeting is to vote on:

Recommendation of the Engility Board

The Engility Board unanimously has determined that the merger agreement and the transactions contemplated by it are advisable and in the best interests of Engility and its stockholders and has unanimously approved the merger agreement and the transactions contemplated by it, including the merger.

The Engility Board unanimously recommends that the Engility stockholders vote “FOR” the approval of the Engility merger proposal, “FOR” the approval of the Engility compensation proposal and “FOR” the Engility adjournment proposal.

See the section entitled “The Merger and the Stock Issuance—Engility’s Reasons for the Merger; Recommendation of the Merger by the Engility Board” beginning on page 53 for a more detailed discussion of the Engility Board’s recommendation.

Record Date; Stock Entitled to Vote

The close of business on November 29, 2018 has been fixed as the record date for determining the Engility stockholders entitled to receive notice of and to vote at the Engility special meeting. On the record date, 36,968,909 shares of Engility common stock were outstanding.

Voting of Proxies

Each copy of this document mailed to holders of Engility common stock as of the record date is accompanied by a form of proxy with instructions for voting by mail, by telephone or through the Internet. If you hold stock in your name as a stockholder of record and are voting by mail, you should complete and return the proxy card accompanying this document to ensure that your vote is counted at the Engility special meeting, or at any adjournment or postponement of the special meeting, regardless of whether or not you plan to attend the Engility special meeting. You may also vote your shares by telephone or through the Internet. Information and applicable deadlines for voting by telephone or through the Internet are set forth in the enclosed proxy card instructions.

If you hold your stock in “street name” through a bank, broker, trust company or other nominee, you must direct your bank, broker, trust company or other nominee to vote in accordance with the instructions you have received from your bank, broker, trust company or other nominee.

All shares represented by valid proxies that are received through this solicitation, and that are not revoked, will be voted in accordance with your instructions on the proxy card or as instructed via the Internet or telephone. If you make no specification on your proxy card as to how you want your shares voted, your signed proxy will be voted “FOR” the approval of the Engility merger proposal, “FOR” the approval of the Engility compensation proposal and “FOR” the approval of the Engility adjournment proposal. According to the Engility bylaws, only such business that is specified in Engility’s notice of the meeting may be conducted at a special meeting of stockholders.

Revoking Your Proxy

If you are a stockholder of record, you may revoke your proxy at any time before it is voted at the Engility special meeting. To do this, you must:

If your shares are held in “street name,” you must contact your broker or nominee to revoke and vote your proxy.

Solicitation of Proxies

In accordance with the merger agreement, the cost of proxy solicitation for the Engility special meeting will be borne by Engility, other than expenses incurred by SAIC and Engility in connection with the filing, printing and mailing of this joint proxy statement/prospectus, half of which expenses will be borne by each of SAIC and Engility. In addition to the use of the mail, proxies may be solicited by officers and directors and regular employees of Engility, without additional remuneration, by personal interview, telephone, facsimile or otherwise. Engility will also request brokerage firms, nominees, custodians and fiduciaries to forward proxy materials to the beneficial owners of shares held of record on the record date and will provide customary reimbursement to such firms for the cost of forwarding these materials. Engility has retained D.F. King & Co., Inc. to assist in its solicitation of proxies and has agreed to pay them a fee of $20,000, plus reasonable expenses, for these services.

Quorum

Stockholders who hold shares representing at least a majority of the issued and outstanding shares entitled to vote at the Engility special meeting must be present in person or represented by proxy to constitute a quorum for the transaction of business at the Engility special meeting. The chairman of the Engility special meeting, whether or not a quorum is present, may adjourn the Engility special meeting to another time and place. At any adjourned meeting at which a quorum shall be present, any business may be transacted that might have been transacted at the original meeting. When a meeting is adjourned to another time or place, notice need not be given of the adjourned meeting if the time and place, if any, thereof, and the means of remote communications, if any, by which stockholders and proxyholders may be deemed to be present in person and vote at such adjourned meeting are announced at the meeting at which the adjournment is taken; provided, however, that if the date of any adjourned meeting is more than 30 days after the date for which the meeting was originally noticed, notice of the place, if any, date, and time of the adjourned meeting and the means of remote communications, if any, by which stockholders and proxyholders may be deemed to be present in person and vote at such adjourned meeting, shall be given to each stockholder in conformity with the Engility bylaws.

Abstentions and broker non-votes will be included in the calculation of the number of shares of Engility common stock represented at the special meeting for purposes of determining whether a quorum has been achieved.

Vote Required

Each share of Engility common stock outstanding on the record date for the Engility special meeting entitles the holder to one vote on each matter to be voted upon at the Engility special meeting. Each of the proposals has the following vote requirement in order to be approved:

Abstentions and Broker Non-Votes

Abstentions, failures to submit a proxy card or vote in person, by telephone, or through the Internet and broker non-votes will be treated in the following manner with respect to determining the votes received for each of the proposals:

Voting Agreement with Birch Partners, L.P.

Birch entered into the voting agreement with SAIC and Engility and, for purposes of certain sections thereof, certain investment funds affiliated with KKR and certain investment funds affiliated with GA. Birch owns 17,920,892 Covered Shares (or approximately 48.48% of the total outstanding shares, of Engility common stock as of September 5, 2018). Subject to the terms and conditions set forth in the voting agreement, Birch has agreed, among ot