UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 ------------- SCHEDULE 13D UNDER THE SECURITIES EXCHANGE ACT OF 1934 (AMENDMENT NO. 3)* TransAlta Corporation ------------------------------------------------------------------------------- (Name of Issuer) Common Stock ------------------------------------------------------------------------------- (Title of Class of Securities) 89346D107 ------------------------------------------------------------------------------- (CUSIP Number) Mr. Christopher Hohn The Children's Investment Fund Management (UK) LLP 7 Clifford Street London W1S 2WE United Kingdom +44 20 7440 2330 With a copy to: Marc Weingarten, Esq. Schulte Roth & Zabel LLP 919 Third Avenue New York, New York 10022 (212) 756-2000 ------------------------------------------------------------------------------- (Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications) (Continued on following pages) February 27, 2009 ------------------------------------------------------------------------------- (Date of Event which Requires Filing of This Statement) If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of Rule 13d-1(e), 13d-1(f) or 13d-1(g), check the following box. [ ] NOTE: Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits. See Rule 13d-7 for other parties to whom copies are to be sent. -------------------------- * The remainder of this cover page shall be filled out for a reporting person's initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter disclosures provided in a prior cover page. The information required on the remainder of this cover page shall not be deemed to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes). (Page 1 of 8 Pages) -------------------------------------------------------------------------------- CUSIP NO. 89346D107 SCHEDULE 13D PAGE 2 OF 8 Pages -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- 1 NAME OF REPORTING PERSON I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY) The Children's Investment Fund Management (UK) LLP ----------------------------------------------------------------------------- 2 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP* (a) [ ] (b) [ ] ----------------------------------------------------------------------------- 3 SEC USE ONLY ----------------------------------------------------------------------------- 4 SOURCE OF FUNDS* AF ----------------------------------------------------------------------------- 5 CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) or 2(e) [X] ----------------------------------------------------------------------------- 6 CITIZENSHIP OR PLACE OF ORGANIZATION England ----------------------------------------------------------------------------- 7 SOLE VOTING POWER -0- ----------------------------------------------------------------------------- NUMBER OF 8 SHARED VOTING POWER SHARES BENEFICIALLY 9,804,900 OWNED BY ------------------------------------------------------- EACH 9 SOLE DISPOSITIVE POWER REPORTING PERSON WITH -0- ------------------------------------------------------- 10 SHARED DISPOSITIVE POWER 9,804,900 ----------------------------------------------------------------------------- 11 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 4.96% ----------------------------------------------------------------------------- 12 CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES* [ ] ----------------------------------------------------------------------------- 13 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 4.96% ----------------------------------------------------------------------------- 14 TYPE OF REPORTING PERSON* PN ----------------------------------------------------------------------------- -------------------------------------------------------------------------------- CUSIP NO. 89346D107 SCHEDULE 13D PAGE 3 OF 8 Pages -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- 1 NAME OF REPORTING PERSON I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY) The Children's Investment Fund Management (Cayman) Ltd. ----------------------------------------------------------------------------- 2 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP* (a) [ ] (b) [ ] ----------------------------------------------------------------------------- 3 SEC USE ONLY ----------------------------------------------------------------------------- 4 SOURCE OF FUNDS* AF ----------------------------------------------------------------------------- 5 CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) or 2(e) [X] ----------------------------------------------------------------------------- 6 CITIZENSHIP OR PLACE OF ORGANIZATION Cayman Islands ----------------------------------------------------------------------------- 7 SOLE VOTING POWER -0- ----------------------------------------------------------------------------- NUMBER OF 8 SHARED VOTING POWER SHARES BENEFICIALLY 9,804,900 OWNED BY ------------------------------------------------------- EACH 9 SOLE DISPOSITIVE POWER REPORTING PERSON WITH -0- ------------------------------------------------------- 10 SHARED DISPOSITIVE POWER 9,804,900 ----------------------------------------------------------------------------- 11 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 4.96% ----------------------------------------------------------------------------- 12 CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES* [ ] ----------------------------------------------------------------------------- 13 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 4.96% ----------------------------------------------------------------------------- 14 TYPE OF REPORTING PERSON* CO ----------------------------------------------------------------------------- -------------------------------------------------------------------------------- CUSIP NO. 89346D107 SCHEDULE 13D PAGE 4 OF 8 Pages -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- 1 NAME OF REPORTING PERSON I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY) The Children's Investment Master Fund ----------------------------------------------------------------------------- 2 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP* (a) [ ] (b) [ ] ----------------------------------------------------------------------------- 3 SEC USE ONLY ----------------------------------------------------------------------------- 4 SOURCE OF FUNDS* WC ----------------------------------------------------------------------------- 5 CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) or 2(e) [X] ----------------------------------------------------------------------------- 6 CITIZENSHIP OR PLACE OF ORGANIZATION Cayman Islands ----------------------------------------------------------------------------- 7 SOLE VOTING POWER -0- ----------------------------------------------------------------------------- NUMBER OF 8 SHARED VOTING POWER SHARES BENEFICIALLY 9,804,900 OWNED BY ------------------------------------------------------- EACH 9 SOLE DISPOSITIVE POWER REPORTING PERSON WITH -0- ------------------------------------------------------- 10 SHARED DISPOSITIVE POWER 9,804,900 ----------------------------------------------------------------------------- 11 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 4.96% ----------------------------------------------------------------------------- 12 CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES* [ ] ----------------------------------------------------------------------------- 13 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 4.96% ----------------------------------------------------------------------------- 14 TYPE OF REPORTING PERSON* CO ----------------------------------------------------------------------------- -------------------------------------------------------------------------------- CUSIP NO. 89346D107 SCHEDULE 13D PAGE 5 OF 8 Pages -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- 1 NAME OF REPORTING PERSON I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY) Christopher Hohn ----------------------------------------------------------------------------- 2 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP* (a) [ ] (b) [ ] ----------------------------------------------------------------------------- 3 SEC USE ONLY ----------------------------------------------------------------------------- 4 SOURCE OF FUNDS* AF ----------------------------------------------------------------------------- 5 CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) or 2(e) [X] ----------------------------------------------------------------------------- 6 CITIZENSHIP OR PLACE OF ORGANIZATION United Kingdom ----------------------------------------------------------------------------- 7 SOLE VOTING POWER -0- ----------------------------------------------------------------------------- NUMBER OF 8 SHARED VOTING POWER SHARES BENEFICIALLY 9,804,900 OWNED BY ------------------------------------------------------- EACH 9 SOLE DISPOSITIVE POWER REPORTING PERSON WITH -0- ------------------------------------------------------- 10 SHARED DISPOSITIVE POWER 9,804,900 ----------------------------------------------------------------------------- 11 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 4.96% ----------------------------------------------------------------------------- 12 CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES* [ ] ----------------------------------------------------------------------------- 13 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 4.96% ----------------------------------------------------------------------------- 14 TYPE OF REPORTING PERSON* IN ----------------------------------------------------------------------------- -------------------------------------------------------------------------------- CUSIP NO. 89346D107 SCHEDULE 13D PAGE 6 OF 8 Pages -------------------------------------------------------------------------------- The Schedule 13D filed on August 15, 2008 (the "Schedule 13D"), as amended by the Amendment No. 1 filed on September 10, 2008 and the Amendment No. 2 filed on January 16, 2009 by The Children's Investment Fund Management (UK) LLP, an English limited liability partnership, The Children's Investment Fund Management (Cayman) Ltd., a Cayman Islands exempted company, The Children's Investment Master Fund, a Cayman Islands exempted company, and Christopher Hohn (together, the "Reporting Persons") relating to the shares ("Shares") of common stock of TransAlta Corporation (the "Issuer"), is hereby amended as set forth below by this Amendment No. 3 to the Schedule 13D. ITEM 5. INTEREST IN SECURITIES OF THE ISSUER Paragraphs (a), (c) and (e) of Item 5 of the Schedule 13D are hereby amended and restated as follows: (a) As of the close of business on February 27, 2009, the Reporting Persons beneficially owned an aggregate of 9,804,900 Shares, constituting approximately 4.96% of the Shares outstanding. The aggregate percentage of Shares beneficially owned by the Reporting Persons is based upon 197,615,840 Shares outstanding, which is the total number of Shares issued and outstanding as of September 30, 2008 as reported in the Issuer's Amendment No. 1 to Form 10-F filed on November 18, 2008. (c) Information concerning transactions in the Shares effected by the Reporting Persons since the last amendment is set forth in Appendix A hereto and is incorporated herein by reference. (e) The reporting persons ceased to be the beneficial owners of more than five percent of the Shares on February 27, 2009. -------------------------------------------------------------------------------- CUSIP NO. 89346D107 SCHEDULE 13D PAGE 7 OF 8 Pages -------------------------------------------------------------------------------- SIGNATURES After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct. Dated: March 6, 2009 THE CHILDREN'S INVESTMENT FUND MANAGEMENT (UK) LLP /s/ Christopher Hohn ------------------------------ Christopher Hohn Managing Partner THE CHILDREN'S INVESTMENT FUND MANAGEMENT (CAYMAN) LTD. /s/ David DeRosa ------------------------------ David DeRosa Director THE CHILDREN'S INVESTMENT MASTER FUND /s/ David DeRosa ------------------------------ David DeRosa Director /s/ Christopher Hohn ------------------------------ Christopher Hohn -------------------------------------------------------------------------------- CUSIP NO. 89346D107 SCHEDULE 13D PAGE 8 OF 8 Pages -------------------------------------------------------------------------------- APPENDIX A TRANSACTIONS IN THE SHARES EFFECTED BY THE REPORTING PERSONS SINCE THE FILING OF THE SCHEDULE 13D (UNLESS OTHERWISE STATED, ALL TRANSACTIONS WERE EFFECTED IN THE OPEN MARKET) The Children's Investment Master Fund Date of Trade Shares Purchased (Sold) Price per Share(1) 15-Jan-09 (77,100) 18.188 15-Jan-09 (34,000) 18.201 16-Jan-09 (29,300) 18.379 22-Jan-09 (6,300) 17.507 29-Jan-09 (20,200) 18.766 30-Jan-09 (40,345) 18.392 02-Feb-09 (87,300) 18.027 03-Feb-09 (104,200) 18.066 04-Feb-09 (138,700) 18.286 04-Feb-09 (200,000) 18.259 05-Feb-09 (84,000) 18.128 05-Feb-09 (100,000) 18.218 06-Feb-09 (85,200) 18.401 09-Feb-09 (50,000) 18.621 09-Feb-09 (64,500) 18.511 10-Feb-09 (66,700) 17.595 11-Feb-09 (67,000) 17.465 12-Feb-09 (113,400) 17.141 13-Feb-09 (95,900) 17.352 17-Feb-09 (76,764) 16.123 27-Feb-09 (146,100) 16.337 02-Mar-09 (93,100) 15.535 03-Mar-09 (124,900) 15.134 04-Mar-09 (229,900) 15.012 05-Mar-09 (136,100) 14.162 --------------------- (1) US dollar amounts calculated using exchange rates in effect on the date of trade.