EARNINGS PER SHARE
    The computation of basic and diluted earnings per common share for the years ended December 31, 2025, 2024 and 2023 is as follows (in millions, except per share data):
 202520242023
Amounts attributable to Quest Diagnostics’ common stockholders:  
Net income attributable to Quest Diagnostics$992 $871 $854 
Less: Earnings allocated to participating securities
Earnings available to Quest Diagnostics’ common stockholders – basic and diluted
$988 $866 $850 
Weighted average common shares outstanding – basic111 111 112 
Effect of dilutive securities:  
Stock options and performance share units
Weighted average common shares outstanding – diluted113 113 113 
Earnings per share attributable to Quest Diagnostics’ common stockholders:  
Basic$8.87 $7.78 $7.59 
Diluted$8.75 $7.69 $7.49 

About Earnings Per Share Disclosures

The earnings per share disclosure breaks down the calculation from net income to both basic and diluted EPS, revealing the full impact of a company's capital structure on per-share economics. The reconciliation between basic and diluted share counts exposes how many stock options, RSUs, convertible securities, and warrants are potentially dilutive to existing shareholders.

Key signals: a widening gap between basic and diluted shares indicates growing dilution from equity compensation or convertible instruments. Anti-dilutive securities excluded from the diluted calculation deserve attention — they represent latent dilution that will materialize if the stock price rises. Watch for the effect of share buybacks on per-share metrics: EPS growth driven primarily by repurchases rather than income growth signals weakening fundamentals. Compare year-over-year changes in the diluted share count against equity compensation expense to assess whether management is effectively managing dilution.