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. Since we were in a loss position for all periods presented, basic net loss per share attributable to Portola Common Stockholders is the same as diluted net loss per share attributable to Portola Common Stockholders as the inclusion of all potentially dilutive common shares would have been anti-dilutive.

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:

	As of September 30,
	2018		2017
Stock options to purchase common stock		7,200,427		6,421,103
Performance stock options		147,335		176,117
Common stock warrants		1,500		1,500
Restricted stock units		809,014		637,772
Performance stock units		160,378		316,961
Employee stock purchase plan		19,062		7,759

Up to 1.0 million shares may be contingently issued, if certain regulatory and 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.