Company: TSLTF
Filing Date: 2025-12-12
Form Type: SUPPL
Source: 0001193125-25-317786
Chunk: 383

Company: TRANSALTA CORP
Filing Date: 2025-12-12
Form: SUPPL
Chunk 383
---
 86 |   |     |            |  1 |     |       |   182 |   |     |       |  98 |   |     |        |  12 |   |     |     |   104 |   |     |            | 1 |   |     |       |   215 |   |

| (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 adjusted 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.                                   |

Three months ended Sept. 30, 2025 Variance Analysis (2025 versus 2024) Total production for the Alberta portfolio for the three months ended Sept. 30, 2025 was 3,206 GWh compared to 2,768 GWh in the same period of 2024. The increase of 438 GWh, or 16 per cent was primarily due to:

| • |     | Higher contract production in the Gas segment due to the addition of Heartland gas facilities 
 in the fourth quarter of 2024; and                                                            |

| • |     | Higher production from the Hydro segment due to the optimization of water supply to facilitate 
 generation during higher demand periods; partially offset by                                   |

| • |     | Lower merchant production in the Gas segment due to dispatch optimization driven by lower market 
 prices; and                                                                                      |

| • |     | Lower production volumes in the Wind and Solar segment due to lower wind resource in Alberta. |

Hedged volumes for the three months ended Sept. 30, 2025 increased compared to the same period in 2024 in anticipation of the weakening spot market