Company: TSLTF
Filing Date: 2025-12-12
Form Type: SUPPL
Source: 0001193125-25-317786
Chunk: 379

Company: TRANSALTA CORP
Filing Date: 2025-12-12
Form: SUPPL
Chunk 379
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 • |     | Higher volume of favourable hedge positions settled. |

Adjusted EBITDA for the three months ended Sept. 30, 2025 decreased compared to the same period in 2024, primarily due to:

| • |     | Lower adjusted revenues as explained above; partially offset by |

| • |     | Lower purchased power costs due to fewer repurchases to fulfill contractual obligations during 
 outages.                                                                                       |

Adjusted earnings before income taxes for the three months ended Sept. 30, 2025 were comparable to the same period in 2024. Earnings before income taxes for the three months ended Sept. 30, 2025 increased compared to the same period in 2024 due to lower asset impairment charges related to changes in decommissioning and restoration provision on retired assets. Mine reclamation spend for the three months ended Sept. 30, 2025 was consistent with the same period in 2024. Adjusted revenues for the nine months ended Sept. 30, 2025 decreased compared to the same period in 2024, primarily due to:

| • |     | Lower Mid-Columbia prices; partially offset by |

| • |     | Favourable hedge positions settled, which generated positive contributions over settled spot 
 prices.                                                                                      |

Adjusted EBITDA for the nine months ended Sept. 30, 2025 increased compared to the same period in 2024 due to:

| • |     | Lower purchased power costs driven by higher availability, which resulted in fewer repurchases to 
 fulfill contractual obligations during outages; partially offset by                               |

| • |     | Lower adjusted revenues as explained above; and |

| • |     | Higher OM&A related to community fund spending. |

Adjusted earnings before income taxes for the nine months ended Sept. 30, 2025 increased compared to the same period in 2024 due to higher adjusted EBITDA as explained above. Earnings before income taxes for the nine months ended Sept. 30, 2025 increased compared to the same period in 2024 due to:

| • |     | Higher adjusted earnings before income taxes as explained above; and |

| • |     | Impairment reversal related to generation equipment in the current period; partially offset by |

| • |     | Higher unrealized                                                              
 mark-to-market losses due to less favourable hedges in the current period; and |

| • |     | Higher asset impairment charges related to an increase in decommissioning and restoration provision