13. Net loss per share

The Company computes net loss per share using the two-class method. The two-class method uses an earnings allocation formula that determines net loss per share for common stock and any participating securities according to dividends declared and participation rights in undistributed earnings.

Diluted net loss per share includes the potential dilutive effect of common stock equivalents as if such securities were converted or exercised during the period, when the effect is dilutive. Common stock equivalents include: (i) outstanding stock options and restricted stock units; (ii) common stock to be issued upon the assumed exercise of the Company's common stock warrants; and (iii) prior to issuance, the contingently issuable warrants related to the Company’s March private placement financing. Because the impact of these items is generally anti-dilutive during periods of net loss, there is no difference between basic and diluted loss per common share for periods with net losses. 

The following table sets forth the computation of basic and diluted net loss per share of common and preferred stock (in thousands, except share and per share data):

The following outstanding shares of potentially dilutive securities were excluded from the computation of diluted net loss per share for the periods presented because including them would have been antidilutive: