8. Earnings Per Share of Common Stock

The following table presents a reconciliation of the earnings and share data used in the basic and diluted earnings per share computations for the three months ended March 31, 2018 and 2017:


	Three Months Ended March 31,
	2018		2017
	($ in millions, except share amounts)
Net earnings available to Alleghany stockholders	$	171.6	$	149.2
Effect of dilutive securities		(1.3)		-

Income available to common stockholders for diluted earnings per share	$	170.3	$	149.2


Weighted average common shares outstanding applicable to basic earnings per share		15,389,283		15,413,698
Effect of dilutive securities		29,381		6,770

Adjusted weighted average common shares outstanding applicable to diluted earnings per share		15,418,664		15,420,468

23,777 and 57,756 contingently issuable shares were potentially available during the first three months of 2018 and 2017, respectively, but were not included in the diluted earnings per share computations because the impact was anti-dilutive to the earnings per share calculation.