4. Loss Per Share

The Company calculates net loss per share in accordance with ASC 260, Earnings Per Share. Under the provisions of ASC 260, basic net loss per share is computed by dividing the net loss for the period by the weighted average number of shares of common stock outstanding for the period. Diluted net loss per share is computed by dividing the net loss by the weighted average number of shares of common stock and dilutive common stock equivalents then outstanding. Common stock equivalents consist of shares of common stock issuable upon the exercise of stock options and warrants.

The following table sets forth the computation for basic and diluted loss per share:

	Three Months Ended March 31,
	2014		2015

Numerator:
Net loss	$	(3,504,439)	$	(4,018,380)
Numerator for basic and diluted earnings per share	$	(3,504,439)	$	(4,018,380)
Denominator:
Denominator for basic and diluted earnings per share — weighted-average shares		38,718,336		38,795,396
Basic and diluted loss per share	$	(0.09)	$	(0.10)

Outstanding stock options to purchase 2,217,134 and 2,461,078 shares of common stock of the Company for the periods ended March 31, 2014 and 2015, respectively, were excluded from the calculation of diluted loss per share as their effect would have been antidilutive. Also excluded from the calculation were 270,000 unvested shares of restricted common stock for both of the periods ended March 31, 2014 and 2015. Outstanding warrants to purchase 1,258,013 shares of common stock of the Company for the period ended March 31, 2015 were also excluded in the calculation of diluted loss per share.