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v3.25.3

Shareholders' Equity (Tables) | 12 Months Ended
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Sep. 30, 2025
Shareholders' Equity |
Schedule of Accumulated Other Comprehensive Income (Loss) |
|  | Net |  |  | Defined Benefit |  |  | Net Unrealized |  |  |  |
|  | Unrealized |  |  | Pension and |  |  | Gain (Loss) on |  |  |  |
|  | Gain (Loss) |  |  | Other |  |  | Available-for- |  |  |  |
|  | on Cash Flow |  |  | Postretirement |  |  | Sale Debt |  |  |  |
|  | Hedges |  |  | Benefit Plans |  |  | Securities |  |  | Total |
Spire |  |  |  |  |  |  |  |  |  |  |  |
Balance at September 30, 2023 |  | $ | 50.5 |  |  | $ | (2.5 | ) |  | $ | (0.4 | ) |  | $ | 47.6 |
Other comprehensive (loss) income |  |  | (36.3 | ) |  |  | 0.5 |  |  |  | 0.3 |  |  |  | (35.5 | )
Balance at September 30, 2024 |  |  | 14.2 |  |  |  | (2.0 | ) |  |  | (0.1 | ) |  |  | 12.1 |
Other comprehensive income |  |  | 5.9 |  |  |  | 1.3 |  |  |  | 0.1 |  |  |  | 7.3 |
Balance at September 30, 2025 |  | $ | 20.1 |  |  | $ | (0.7 | ) |  | $ | — |  |  | $ | 19.4 |
Spire Missouri |  |  |  |  |  |  |  |  |  |  |  |
Balance at September 30, 2023 |  | $ | — |  |  | $ | (2.5 | ) |  | $ | — |  |  | $ | (2.5 | )
Other comprehensive income |  |  | — |  |  |  | 0.5 |  |  |  | — |  |  |  | 0.5 |
Balance at September 30, 2024 |  |  | — |  |  |  | (2.0 | ) |  |  | — |  |  |  | (2.0 | )
Other comprehensive income |  |  | — |  |  |  | 1.3 |  |  |  | — |  |  |  | 1.3 |
Balance at September 30, 2025 |  | $ | — |  |  | $ | (0.7 | ) |  | $ | — |  |  | $ | (0.7 | )

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