Net Income Per Share
Basic net income per share is computed based on the weighted average number of common shares (including participating securities) issued and outstanding during the period. Diluted net income per share is computed based on the weighted average number of common shares issued and outstanding plus equivalent shares, assuming the exercise of stock options. The dilutive effect of stock options is computed by application of the treasury-stock method. The weighted average number of common shares outstanding for 2016 and 2017 reflect the 2-for-1 stock split that occurred on March 28, 2018.
The following is a reconciliation between basic and diluted weighted average shares outstanding for the years ended December 31:
 
(in thousands, except per share data)
2018
 
2017(1)
 
2016(1)
Net income
$
344,255

 
$
399,630

 
$
257,491

Net income attributable to unvested awarded performance stock
(8,297
)
 
(9,746
)
 
(6,705
)
Net income attributable to common shares
$
335,958

 
$
389,884

 
$
250,786

Weighted average number of common shares outstanding – basic
277,663

 
279,394

 
279,558

Less unvested awarded performance stock included in weighted average number of common shares outstanding – basic
(6,692
)
 
(6,814
)
 
(7,280
)
Weighted average number of common shares outstanding for basic earnings per common share
270,971

 
272,580

 
272,278

Dilutive effect of stock options
4,550

 
5,006

 
3,330

Weighted average number of shares outstanding – diluted
275,521

 
277,586

 
275,608

Net income per share:
 
 
 
 
 
Basic
$
1.24

 
$
1.43

 
$
0.92

Diluted
$
1.22

 
$
1.40

 
$
0.91


(1)
The weighted average number of common shares outstanding for 2016 and 2017 reflect the 2-for-1 stock split that occurred on March 28, 2018.

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.