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v3.23.3

Per Share Information (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions | 3 Months Ended | 9 Months Ended |  |  |
--- | --- | --- | --- | --- | ---
Sep. 30, 2023 | Sep. 30, 2022 | Sep. 30, 2023 | Sep. 30, 2022 | Apr. 28, 2023 | Dec. 31, 2022 | Feb. 02, 2022
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |  |  |  |  |  |  |
Net income attributable to ATI | $ 75.7 | $ 61.1 | $ 221.8 | $ 54.0 |  |  |
Net income attributable to ATI after assumed conversions | $ 78.4 | $ 63.9 | $ 229.7 | $ 54.0 |  |  |
Denominator for basic net income per common share – weighted average shares | 128.1 | 129.8 | 128.4 | 126.9 |  |  |
Share-based compensation | 3.3 | 2.2 | 2.9 | 2.0 |  |  |
Denominator for diluted net income per common share – adjusted weighted average shares and assumed conversions | 150.2 | 150.8 | 150.1 | 128.9 |  |  |
Basic net income (loss) attributable to ATI per common share (in dollars per share) | $ 0.59 | $ 0.47 | $ 1.73 | $ 0.43 |  |  |
Diluted net income (loss) attributable to ATI per common share (in dollars per share) | $ 0.52 | $ 0.42 | $ 1.53 | $ 0.42 |  |  |
Antidilutive Securities Excluded from Computation of Earnings Per Share Amount | 0.0 | 0.0 | 0.0 | 22.5 |  |  |
Purchase of treasury stock | $ (45.0) | $ (15.0) | $ (55.1) | $ (104.9) |  |  |
Stock repurchase plan, authorized amount |  |  |  |  | $ 75.0 |  | $ 150.0
Treasury Stock, Shares, Acquired | 1.0 | 0.5 | 1.2 | 4.0 |  |  |
Purchase of treasury stock | $ (45.4) | $ (15.0) | $ (55.5) | $ (104.9) |  |  |
Treasury Stock |  |  |  |  |  |  |
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |  |  |  |  |  |  |
Purchase of treasury stock | (45.4) | (15.0) | (55.5) | (104.9) |  |  |
ATI Inc. 3.5% Convertible Senior Notes due 2025 |  |  |  |  |  |  |
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |  |  |  |  |  |  |
Convertible Senior Notes- Effect on numerator | $ 2.7 | $ 2.8 | $ 7.9 | $ 0.0 |  |  |
Convertible Senior Notes- Effect on denominator | 18.8 | 18.8 | 18.8 | 0.0 |  |  |
ATI Inc. 3.5% Convertible Senior Notes due 2025 | Convertible Debt |  |  |  |  |  |  |
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |  |  |  |  |  |  |
Interest rate | 3.50% |  | 3.50% |  |  | 3.50% |

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