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v3.24.1.u1

Per Share Information (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions | 3 Months Ended |  |
--- | --- | --- | ---
Mar. 31, 2024 | Apr. 02, 2023 | Dec. 31, 2023 | Nov. 30, 2023
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |  |  |  |
Net income attributable to ATI | $ 66.1 | $ 84.5 |  |
Net income attributable to ATI after assumed conversions | $ 68.2 | $ 87.1 |  |
Denominator for basic net income per common share – weighted average shares | 126.2 | 128.5 |  |
Share-based compensation | 2.5 | 2.8 |  |
Denominator for diluted net income per common share – adjusted weighted average shares and assumed conversions | 147.5 | 150.1 |  |
Basic net income attributable to ATI per common share (in dollars per share) | $ 0.52 | $ 0.66 |  |
Diluted net income attributable to ATI per common share (in dollars per share) | $ 0.46 | $ 0.58 |  |
Antidilutive Securities Excluded from Computation of Earnings Per Share Amount | 0.0 | 0.0 |  |
Purchase of treasury stock | $ (150.0) | $ (10.1) |  |
Stock repurchase plan, authorized amount |  |  |  | $ 150.0
Treasury Stock, Shares, Acquired | 3.4 | 0.2 |  |
Purchase of treasury stock | $ (151.2) | $ (10.1) |  |
Treasury Stock |  |  |  |
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |  |  |  |
Purchase of treasury stock | (151.2) | (10.1) |  |
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 | $ 2.1 | $ 2.6 |  |
Convertible Senior Notes- Effect on denominator | 18.8 | 18.8 |  |
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% |

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