Company: TSLTF
Filing Date: 2025-12-12
Form Type: SUPPL
Source: 0001193125-25-317786
Chunk: 384

Company: TRANSALTA CORP
Filing Date: 2025-12-12
Form: SUPPL
Chunk 384
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     — |   |     |          |     2 |   |     |        |    51 |   |     |            |  — |     |       |    53 |   |     |       |     — |   |     |        |     — |   |     |     |    91 |   |     |            |  1 |     |       |    92 |   |
| Adjusted gross margin(2) ($)        |     |       |   272 |   |     |          |    66 |   |     |        |   273 |   |     |            |  4 |     |       |   615 |   |     |       |   287 |   |     |        |    71 |   |     |     |   296 |   |     |            |  3 |     |       |   657 |   |

| (1) | Total production includes contract and merchant production. |

| (2) | Revenues have been adjusted to exclude the impact of unrealized mark-to-market gains or losses. During the first quarter of 2025, our Adjusted revenues and gross margin composition was amended to exclude the impact of realized gain (loss) on closed exchange positions. 
 Therefore, the Company has applied this composition to all previously reported periods.                                                                                                                                                                                      |

| (3) | The intercompany sales of emission credits from the Hydro and Wind and Solar segments to the Gas                                                   
 segment are eliminated on consolidation in the Corporate segment. Refer to the Non-IFRS and Supplementary Financial Measures section of this MD&A. |

| (4) | Gross installed capacity for Wind and Solar was reduced due to tower removal at Sinott. |

| (5) | Gross installed capacity for Alberta facilities in 2025 includes 1,687 MW from the acquisition of 
 Heartland and excludes capacity from the Required Divestitures.                                   |

| TransAlta Corporation |     | M37 |

Management’s Discussion and Analysis

Nine months ended Sept. 30, 2025 Variance Analysis (2025 versus 2024) Total production for the Alberta portfolio for the nine months ended Sept. 30, 2025 was 8,868 GWh compared to 8,659 GWh in the same period of 2024. The increase of 209 GWh, or two per cent was primarily due to:

| • |     | Higher contract production in the Gas segment