| Net Income Per Share |
13. NET INCOME PER SHARE Basic net income per share is calculated by dividing net income by the weighted average shares outstanding during the period, without consideration for common stock equivalents. Diluted net income per share is calculated by adjusting weighted average shares outstanding for the dilutive effect of common stock equivalents outstanding for the period, determined using the treasury stock method. Basic and diluted net income per share were computed as follows: | | | | | | | | | | | | Years Ended December 31, | | | 2023 | | 2022 | | 2021 | Net income (in thousands) | | $ | 614,254 | | $ | 555,989 | | $ | 324,016 | | | | | | | | | | | Weighted average number of common shares outstanding - basic | | | 31,597,508 | | | 32,213,839 | | | 32,801,906 | | | | | | | | | | | Dilutive effect of common stock equivalents: | | | | | | | | | | RSAs with service-based conditions | | | 30,368 | | | 15,199 | | | 21,130 | RSAs with market-based conditions | | | 37,519 | | | 59,561 | | | 127,723 | RSAs with performance-based conditions | | | 25,645 | | | 46,601 | | | 65,262 | Stock options | | | 85,861 | | | 105,205 | | | 130,150 | | | | | | | | | | | Weighted average number of common shares outstanding - diluted | | | 31,776,901 | | | 32,440,405 | | | 33,146,171 | | | | | | | | | | | Basic net income per common share | | $ | 19.44 | | $ | 17.26 | | $ | 9.88 | | | | | | | | | | | Diluted net income per common share | | $ | 19.33 | | $ | 17.14 | | $ | 9.78 |
The following table summarizes shares excluded from the calculation of diluted net income per share because their effect would have been anti-dilutive: | | | | | | | | | | | | Year Ended December 31, | | | 2023 | | 2022 | | 2021 | Anti-dilutive common stock equivalents: | | | | | | | | | | RSAs with service-based conditions | | | - | | | 14,882 | | | 1,206 | RSAs with market-based conditions | | | 3,876 | | | 157 | | | 6,926 | RSAs with performance-based conditions | | | - | | | 9,251 | | | - | Stock options | | | 504 | | | 21,006 | | | 19,121 | Total anti-dilutive common stock equivalents | | | 4,380 | | | 45,296 | | | 27,253 |
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