Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2014

Stock-Based Compensation Expense

The following table presents stock-based compensation expense included in the Company’s consolidated statements of comprehensive income:

	Three months ended June 30,				Six months ended June 30,
	2014		2013		2014		2013
Cost of product revenue	$	63,285	$	11,428	$	89,848	$	23,093
Research and development		80,392		36,081		111,995		43,721
Selling, general and administrative		401,535		265,182		650,794		495,948
Total	$	545,212	$	312,691	$	852,637	$	562,762

Summary of Option Activity

Information regarding option activity for the six months ended June 30, 2014 under the Plans is summarized below:

	Options Outstanding			Weighted- Average Exercise Price Per Share		Weighted- Average Remaining Contractual Term (in years)		Aggregate Intrinsic Value
Options outstanding at January 1, 2014		1,610,988		$	5.07
Granted		339,698			12.37
Exercised		(573,238	)		4.36
Forfeited/Cancelled		(64,707	)		6.92
Options outstanding at June 30, 2014		1,312,741		$	7.19		7.63	$	20,475,525
Options exercisable at June 30, 2014		419,600		$	4.05		5.11	$	7,862,172
Vested and expected to vest at June 30, 2014 (1)		1,211,138		$	7.09		7.56	$	19,013,813

(1) This represents the number of vested options as of June 30, 2014 plus the number of unvested options expected to vest as of June 30, 2014 based on the unvested outstanding options at June 30, 2014 adjusted for estimated forfeiture rates of 8% for awards granted to non-executive level employees and 3% for awards granted to executive level employees.