Net Loss Per Share

12 Months Ended

Dec. 31, 2013

Earnings Per Share [Abstract]

Net Loss Per Share

6. Net Loss per share

Basic and diluted net loss per share attributable to common stockholders has been calculated by dividing net loss attributable to common stockholders by the weighted average number of common shares outstanding during the period. All potentially dilutive common shares have been excluded from the calculation of weighted average common shares outstanding since their inclusion would be anti-dilutive.

Stock options to purchase approximately 3.0 million shares of common stock were outstanding at December 31, 2013 and 2012, but were not included in the computation of diluted net loss per common share because they were anti-dilutive. Common stock equivalents in the form of convertible redeemable preferred stock were not included in the calculation of net loss per share at December 31, 2013 and 2012 as their inclusion would be anti-dilutive. The exercise of stock options outstanding at December 31, 2013 could potentially dilute earnings per share in the future.