Stock-based Compensation

6 Months Ended

Jun. 30, 2013

Stock-based Compensation [Abstract]

Stock-based Compensation

Note 5:  Stock-based Compensation 

The Company uses the fair value method of accounting for share-based compensation arrangements. The fair value of stock options is estimated at the date of grant using the Black-Scholes option valuation model.  Stock-based compensation expense is reduced for estimated forfeitures and is amortized over the vesting period using the straight-line method. 

The following table summarizes the allocation of non-cash stock-based compensation to our expense categories for the three and six month periods ended June 30, 2013 and 2012 (in thousands): 

	Three Months Ended				Six Months Ended
	June 30,				June 30,
	(unaudited)				(unaudited)
	2013		2012		2013		2012
Cost of revenue	$	72	$	72	$	151	$	136
Research and development		137		146		292		287
Selling, general and administrative		250		433		635		977
Total stock compensation expense	$	459	$	651	$	1,078	$	1,400

At June 30, 2013, total unrecognized compensation costs related to stock options was approximately $1.9 million, net of estimated forfeitures.  Total unrecognized compensation cost will be adjusted for future changes in estimated forfeitures and is expected to be recognized over a weighted average period of approximately 1.8 years.   

The following key assumptions were used in the Black-Scholes option pricing model to determine the fair value of stock options granted: 

	For the Six Months Ended
	June 30,
	2013		2012
Dividend yield	0	%	0	%
Risk free interest rates	0.35 – 1.48	%	0.36 - 0.87	%
Expected  volatility	70.9 to 73.8	%	71.8 to 81.2	%
Expected term (in years)	3.5 to 5.0		3.0 to 5.5

The Company paid a special one-time dividend in 2012.  However, the Company does not expect to continue to pay dividends in the near future therefore the Company used an expected dividend yield of 0%.  The risk-free interest rate used in the Black-Scholes option pricing model is based on the implied yield currently available on U.S. Treasury securities with an equivalent term.   Expected volatility is based on the weighted average historical volatility of the Company’s common stock for the equivalent term.  The expected term of options represents the period that our stock-based awards are expected to be outstanding and was determined based on historical experience and vesting schedules of similar awards. 

A summary of the Company’s stock option activity for the six months ended June 30, 2013 is presented in the following table (unaudited): 

	Number of Shares		Weighted Average Exercise Price		Weighted Average Remaining Contractual Life (In Years)		Aggregate Intrinsic Value
Outstanding at December 31, 2012		4,685,434	$	3.82
Options granted		236,411		3.50
Options exercised		(163,615)		1.57
Options forfeited		(64,949)		4.35
Options cancelled or expired		(87,568)		6.61
Outstanding at June 30, 2013		4,605,713	$	3.83		4.85	$	3,901,599
Vested or expected to vest at June 30, 2013 (1)		4,569,281	$	3.82		4.85	$	3,896,971
Exercisable at June 30, 2013		3,694,946	$	3.52		5.03	$	3,785,907

(1) The expected to vest options are the result of applying the pre-vesting forfeiture rate assumptions to total unvested options.

The aggregate intrinsic value in the table above represents the difference between the exercise price of the underlying options and the quoted price of the Company’s common stock.  For the three and six months ended June 30, 2013, the aggregate intrinsic value of options exercised was $325 thousand and $344 thousand, respectively.   The Company issues new shares of common stock upon exercise of stock options.