11. Net Loss per Share Attributable to Portola Common Stockholders

Basic net loss per share attributable to Portola Common Stockholders has been computed by dividing the net loss attributable to Portola Common Stockholders by the weighted-average number of shares of Common Stock outstanding during the period. Diluted net loss per share attributable to Portola Common Stockholders is calculated by dividing net loss attributable to Portola Common Stockholders by the weighted average number of shares of Common Stock and potential dilutive securities outstanding during the period.

The following outstanding shares of common stock equivalents were excluded from the computation of diluted net loss per share attributable to Portola Common Stockholders for the periods presented because including them would have been antidilutive:

	Three Months Ended June 30,				Six Months Ended June 30,
	2018		2017		2018		2017
Stock options to purchase common stock		7,391,411		6,176,302		7,391,411		6,176,302
Performance stock options		155,669		180,752		155,669		180,752
Common stock warrants		1,500		1,500		1,500		1,500
Restricted stock units		749,412		646,653		749,412		646,653
Performance stock units		330,416		368,418		330,416		368,418
Employee stock purchase plan		47,743		22,982		47,743		22,982

Up to 1.0 million shares may be contingently issued, if certain performance conditions are met under an agreement with one of our contract manufacturers, as described in Note 7, Contract Manufacturing Agreements, to these condensed consolidated financial statements.