Ownership Submission
FORM 4
Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).
UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940
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(Print or Type Responses)
1. Name and Address of Reporting Person *
RIO TINTO PLC
  2. Issuer Name and Ticker or Trading Symbol
CLOUD PEAK ENERGY INC. [CLD]
5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
__X__ Director __X__ 10% Owner
_____ Officer (give title below) _____ Other (specify below)
(Last)
(First)
(Middle)
2 EASTBOURNE TERRACE
3. Date of Earliest Transaction (Month/Day/Year)
12/21/2010
(Street)

LONDON, X0 W2 6LG
4. If Amendment, Date Original Filed(Month/Day/Year)
6. Individual or Joint/Group Filing(Check Applicable Line)
___ Form filed by One Reporting Person
_X_ Form filed by More than One Reporting Person
(City)
(State)
(Zip)
Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1.Title of Security
(Instr. 3)
2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 3. Transaction Code
(Instr. 8)
4. Securities Acquired (A) or Disposed of (D)
(Instr. 3, 4 and 5)
5. Amount of Securities Beneficially Owned Following Reported Transaction(s)
(Instr. 3 and 4)
6. Ownership Form: Direct (D) or Indirect (I)
(Instr. 4)
7. Nature of Indirect Beneficial Ownership
(Instr. 4)
Code V Amount (A) or (D) Price
Common Stock 12/21/2010   C   29,400,000 A (1) 29,400,000 I See footnote (2)
Common Stock 12/21/2010   S   29,400,000 D $ 19.5 0 I See footnote (2)

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security
(Instr. 3)
2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (Month/Day/Year) 3A. Deemed Execution Date, if any (Month/Day/Year) 4. Transaction Code
(Instr. 8)
5. Number of Derivative Securities Acquired (A) or Disposed of (D)
(Instr. 3, 4, and 5)
6. Date Exercisable and Expiration Date
(Month/Day/Year)
7. Title and Amount of Underlying Securities
(Instr. 3 and 4)
8. Price of Derivative Security
(Instr. 5)
9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s)
(Instr. 4)
10. Ownership Form of Derivative Security: Direct (D) or Indirect (I)
(Instr. 4)
11. Nature of Indirect Beneficial Ownership
(Instr. 4)
Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares
Common Membership Units (1) 12/21/2010   C     29,400,000   (1)   (1) Common Stock, par value $0.01 per share, of CLD 29,400,000 $ 0 0 I (2) See footnote (2)

Reporting Owners

Reporting Owner Name / Address Relationships
 Director  10% Owner  Officer  Other
RIO TINTO PLC
2 EASTBOURNE TERRACE
LONDON, X0 W2 6LG
  X   X    
RIO TINTO EUROPEAN HOLDINGS LTD
2 EASTBOURNE TERRACE
LONDON, X0 W2 6LG
  X   X    
RIO TINTO WESTERN HOLDINGS LTD
2 EASTBOURNE TERRACE
LONDON, X0 W2 6LG
  X   X    
RIO TINTO AMERICA HOLDINGS INC
4700 DAYBREAK PARKWAY
SOUTH JORDAN, UT 84095
  X   X    
RIO TINTO AMERICA INC
4700 DAYBREAK PARKWAY
SOUTH JORDAN, UT 84095
  X   X    
RIO TINTO ENERGY AMERICA INC
4700 DAYBREAK PARKWAY
SOUTH JORDAN, UT 84095
  X   X    
KENNECOTT MANAGEMENT SERVICES CO
4700 DAYBREAK PARKWAY
SOUTH JORDAN, UT 84095
  X   X    

Signatures

 RIO TINTO plc, By: /s/ Ben Mathews (Secretary)   12/21/2010
**Signature of Reporting Person Date

 RIO TINTO EUROPEAN HOLDINGS LIMITED, By: /s/ Ben Mathews (Director)   12/21/2010
**Signature of Reporting Person Date

 RIO TINTO WESTERN HOLDINGS LIMITED, By: /s/ Ben Mathews (Director)   12/21/2010
**Signature of Reporting Person Date

 RIO TINTO AMERICA HOLDINGS INC., By: /s/ James Berson (Attorney in Fact)   12/21/2010
**Signature of Reporting Person Date

 RIO TINTO AMERICA, By: /s/ James Berson (Attorney in Fact)   12/21/2010
**Signature of Reporting Person Date

 RIO TINTO ENERGY AMERICA, By: /s/ James Berson (Operating Officer)   12/21/2010
**Signature of Reporting Person Date

 KENNECOTT MANAGEMENT SERVICES COMPANY, By: /s/ James Berson (Operating Officer)   12/21/2010
**Signature of Reporting Person Date

Explanation of Responses:

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1) For text of footnote 1, see Exhibit 99.1.
(2) For text of footnote 2, see Exhibit 99.1.

Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.

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