Stock-Based Compensation

6 Months Ended

Sep. 30, 2015

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

STOCK-BASED COMPENSATION

STOCK-BASED COMPENSATION

Stock-based compensation cost is measured at the grant date based on the fair value of the award. The fair value of RSUs is estimated using the Company's stock price on the grant date. The fair value of options and employee stock purchase rights is estimated using the Black-Scholes model on the grant date. The Black-Scholes model determines the fair value of share-based payment awards based on assumptions including the Company's stock price on the date of grant, volatility over the term of the awards, actual and projected employee stock option exercise behaviors and risk free interest rate. The MSUs were valued using the Monte Carlo pricing model, which uses the Company's stock price, the Index value, expected volatilities of the Company's stock price and the Index, correlation coefficients and risk free interest rates to determine the fair value.

The Company did not grant options during the six months ended September 30, 2015.

The fair values of the employee stock purchase rights granted are estimated as of the grant date using the Black-Scholes option-pricing model with the following assumptions:

	Three Months Ended September 30,						Six Months Ended September 30,
	2015			2014			2015			2014
Expected life (years)	0.5			0.5			0.5			0.5
Risk-free interest rate	0.1		%	0.1		%	0.1		%	0.1		%
Volatility	57		%	57		%	57		%	57		%
Weighted average fair value	$	1.80		$	2.57		$	1.80		$	2.57

The weighted average grant-date fair value per share of the RSUs awarded was $6.05 and $6.07 during the three and six months ended September 30, 2015, respectively, as compared to $8.51 and $8.75 during the three and six months ended September 30, 2014, respectively. The weighted average grant-date fair value per share was calculated based on the fair market value of the Company’s common stock on the respective grant dates.

The following tables summarize the allocation of the stock-based compensation expense (in thousands):

Stock-based compensation expense by type of grant:	Three Months Ended September 30,					Six Months Ended September 30,
	2015			2014		2015			2014
Stock options and stock purchase rights	$	289		$	292	$	496		$	706
RSUs	5,650			3,936		11,547			8,720
	5,939			4,228		12,043			9,426
Stock-based compensation (capitalized to) expensed from inventory	(5		)	2		(17		)	20
Total	$	5,934		$	4,230	$	12,026		$	9,446

Stock-based compensation expense by cost centers:	Three Months Ended September 30,					Six Months Ended September 30,
	2015			2014		2015			2014
Cost of revenues	$	121		$	100	$	226		$	129
Research and development	3,955			2,776		8,015			6,047
Selling, general and administrative	1,863			1,352		3,802			3,250
	$	5,939		$	4,228	$	12,043		$	9,426
Stock-based compensation (capitalized to) expensed from inventory	(5		)	2		(17		)	20
Total	$	5,934		$	4,230	$	12,026		$	9,446

As of September 30, 2015, the amount of unrecognized stock-based compensation cost, net of estimated forfeitures, related to unvested stock-based awards was $25.0 million which will be recognized over a weighted average period of 1.2 years.