Basic net loss per share is computed using the weighted-average number of shares of common stock outstanding during the period. Diluted net loss per share is computed using the sum of the weighted-average number of shares of common stock outstanding during the period and if dilutive, the weighted-average number of potential shares of common stock, including unvested restricted common stock and outstanding stock options.

The Company computed basic and diluted net loss per share using the two-class method, which gives effect to the impact of outstanding participating securities. As the three months ended March 31, 2019 and 2018 resulted in net losses attributable to common stockholders, there is no income allocation required under the two-class method or dilution attributed to weighted-average shares outstanding in the calculation of diluted net loss per share because the preferred stockholders do not participate in losses of the Company. Accordingly, for periods in which the Company reports a net loss attributable to common stockholders, diluted net loss per share attributable to common stockholders is the same as basic net loss per share attributable to common stockholders, since dilutive common stock are not assumed to have been issued if their effect is anti-dilutive.

The Company’s potentially dilutive shares, which include outstanding stock options and unvested restricted common stock/units, are considered to be common share equivalents and are only included in the calculation of diluted net loss per share when their effect is dilutive.

The following potential common shares, presented based on amounts outstanding at each period end, were excluded from the calculation of the diluted net loss per share attributable to common stockholders for the period indicated because including them would have had an anti-dilutive effect.

	As of March 31,
	2019		2018
Unvested restricted common stock awards		87,719		320,166
Outstanding options to purchase common stock		2,747,043		1,741,527