Net Income per Common Share

Basic net income per share is computed by dividing net income by the weighted daily average number of shares of common stock outstanding during the period. Diluted net income per share is based upon the weighted daily average number of shares of common stock outstanding for the period plus dilutive potential common shares, including stock options and restricted stock units using the treasury-stock method.

A reconciliation of the weighted average basic common shares outstanding to the weighted average diluted common shares outstanding is as follows:



	Three Months Ended
(millions, except share and per share data) (unaudited)	March 31, 2019		March 31, 2018
Net income attributable to SP Plus Corporation	$	10.6	$	15.3
Basic weighted average common shares outstanding	22,509,050		22,308,694
Dilutive impact of share-based awards	158,489		248,632
Diluted weighted average common shares outstanding	22,667,539		22,557,326
Net income per common share
Basic	$	0.47	$	0.69
Diluted	$	0.47	$	0.68

For the three months ended March 31, 2019 and 2018, unvested performance share units were excluded from the computation of weighted average diluted common share outstanding because the number of shares ultimately issuable is contingent on the Company's performance goals, which were not achieved as of the reporting date.

There are no additional securities that could dilute basic earnings per share in the future that were not included in the computation of diluted earnings per share, other than those disclosed.