Company: TSLTF
Filing Date: 2025-12-12
Form Type: SUPPL
Source: 0001193125-25-317786
Chunk: 448

Company: TRANSALTA CORP
Filing Date: 2025-12-12
Form: SUPPL
Chunk 448
---
 under “Documents Incorporated by Reference”; consent of Ernst & Young LLP; powers of attorney from directors and officers of TransAlta, as applicable; the indenture between TransAlta and The Bank of New York
Mellon, as trustee, dated as of June 25, 2002; and the Statement of Eligibility of The Bank of New York Mellon on Form T-1. A copy of the form of warrant indenture or subscription receipt agreement,
as applicable, will be filed by post-effective amendment or by incorporation by reference to documents filed with or furnished to the SEC under the U.S. Exchange Act.

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US$400,000,000 5.875% Senior Notes due 2034 TransAlta Corporation PROSPECTUS SUPPLEMENT Joint Book-Running Managers

| RBC Capital Markets |     | CIBC Capital Markets |     | BofA Securities |     | Morgan Stanley |

Co-Managers

|                     |     | Scotiabank                 |     |                         |
| BMO Capital Markets |     | TD Securities              |     | National Bank of Canada 
 Capital Markets         |
| ATB Capital Markets |     | Desjardins Capital Markets |     | MUFG                    |
| J.P. Morgan         |     | Mizuho                     |     | Loop Capital Markets    |

December 11, 2025