Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2015

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,
	2015		2014		2015		2014
Cost of product revenue	$	63,068	$	63,285	$	105,975	$	89,848
Research and development		89,905		80,392		159,177		111,995
Selling, general and administrative		831,971		401,535		1,421,774		650,794
Total	$	984,944	$	545,212	$	1,686,926	$	852,637

Summary of Option Activity

Information regarding option activity for the six months ended June 30, 2015 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, 2015		1,225,117		$	8.31
Granted		224,182			14.31
Exercised		(128,613	)		5.03
Forfeited/Cancelled		(55,200	)		8.96
Options outstanding at June 30, 2015		1,265,486		$	9.68		7.23	$	39,977,638
Options exercisable at June 30, 2015		466,706		$	6.21		5.01	$	16,360,523
Vested and expected to vest at June 30, 2015 (1)		1,184,234		$	9.68		7.19	$	37,410,229

⁽¹⁾  Represents the number of vested options as of June 30, 2015 plus the number of unvested options expected to vest as of June 30, 2015 based on the unvested outstanding options at June 30, 2015 adjusted for estimated forfeiture rates of 8% for awards granted to non-executive level employees and 3% for awards granted to executive level employees.