Stockholders' Equity

3 Months Ended

Mar. 31, 2016

Equity [Abstract]

Stockholders' Equity

Stockholders’ Equity

Issuances and Repurchases of Common Stock

During the three months ended March 31, 2016, 74,913 shares of common stock were issued in conjunction with the vesting and release of RSUs, 60,511 shares of common stock were issued due to the exercise of stock options and 41,162 shares of common stock were issued in connection with the Company’s employee stock purchase plan (the “ESPP”), resulting in net proceeds to the Company of approximately $1.6 million. During the three months ended March 31, 2016, 1,152,386 shares of outstanding common stock were repurchased under the Company’s previously announced share repurchase program for approximately $19.6 million. Additionally, 24,932 shares of outstanding common stock were repurchased in connection with payment of minimum tax withholding obligations for certain employees relating to the lapse of restrictions on certain RSUs for approximately $0.4 million. As of March 31, 2016, there was $35.0 million available under the Company’s share repurchase program.

Stock-Based Compensation

The compensation expense related to the Company’s stock-based compensation plans included in the accompanying Consolidated Statements of Operations was as follows (in thousands):

	Three months ended March 31,
	2016			2015
Cost of sales	$	235		$	237
Research and development	297			17
Sales and marketing	(63		)	502
General and administrative	1,511			1,312
Total stock-based compensation expense	$	1,980		$	2,068

Total compensation expense recognized for the three months ended March 31, 2016 includes $1.4 million related to stock options and $0.6 million related to RSUs. Stock-based compensation expense for sales and marketing resulted in a net credit of $0.1 million due to forfeitures of options and RSUs in the first quarter of 2016. Total compensation expense recognized for the three months ended March 31, 2015 includes $1.4 million related to stock options and $0.7 million related to RSUs. As of March 31, 2016, total unrecognized compensation expense related to non-vested stock options was $8.2 million, which is expected to be recognized over a weighted-average period of approximately 2.9 years. As of March 31, 2016, total unrecognized compensation expense related to non-vested RSUs was $3.6 million, which is expected to be recognized over a weighted-average period of approximately 3.0 years. Compensation expense capitalized to inventory and compensation expense related to the Company’s ESPP were not material for the three months ended March 31, 2016 or 2015.

The estimated fair value of each stock option was determined on the date of grant using the Black-Scholes option valuation model with the following weighted-average assumptions for the option grants.

	Three months ended March 31,
	2016		2015
Risk-free interest rate	1.46	%	1.45	%
Expected option life (in years)	6.46		6.22
Volatility rate	36	%	40	%
Dividend rate	—	%	—	%

The weighted-average fair value of stock options granted during the three months ended March 31, 2016 and 2015 was $5.85 and $9.60, respectively. The Company granted 626,413 and 544,247 stock options during the three months ended March 31, 2016 and 2015, respectively. The weighted-average fair value of RSUs granted during the three months ended March 31, 2016 and 2015 was $15.39 and $23.58, respectively. The Company granted 131,972 and 103,118 shares of RSUs during the three months ended March 31, 2016 and 2015, respectively. The fair value of RSUs is determined based on the closing market price of the Company’s common stock on the grant date.