Stock-based Compensation

As of March 30, 2014, the Company had five equity plans. Additional information regarding these plans is disclosed in the Annual Report.

Stock-based compensation expense, net of estimated forfeitures, is recognized on a straight-line basis over the vesting period for each stock option or restricted stock unit ("RSU") grant that is expected to vest at some point in the future. Forfeitures are estimated at the date of grant based on the Company's historical experience and future expectations.

The fair value of each stock option on the date of grant is estimated using the Black-Scholes-Merton option valuation model. The fair value of each RSU is based on the fair market value of the Company's common stock on the date of the grant.

The following weighted average assumptions were used for the valuation of stock options granted during the periods presented:



	Quarter ended
	March 30, 2014			March 31, 2013
Expected term	4.5 years			4.5 years
Expected volatility	46.9		%	57.1		%
Expected dividend yield	0.0		%	0.0		%
Risk-free interest rate	1.5		%	0.9		%
Estimated weighted average fair value per stock option granted	$	13.38		$	14.61

The assumptions used to calculate the fair value of stock options granted are evaluated and revised, if necessary, to reflect market conditions and the Company’s experience.

A summary of stock option activity for the quarter ended March 30, 2014 is as follows:



	Options (in thousands)		Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (in years)	Aggregate Intrinsic Value (in thousands)
Balance, December 30, 2013	1,493		$	41.93
Granted	70		33.25
Exercised	(51	)	21.37
Canceled	(61	)	41.08
Balance, March 30, 2014	1,451		$	42.26	6.03	$	2,221
Vested and expected to vest at March 30, 2014	1,405		$	42.55	5.36	$	2,148
Exercisable, March 30, 2014	1,067		$	45.05	5.05	$	1,650

A summary of RSU activity for the quarter ended March 30, 2014 is as follows:



	RSUs (in thousands)		Weighted Average Grant Date Fair Value		Weighted Average Remaining Contractual Term (in years)	Aggregate Intrinsic Value (in thousands)
Balance, December 30, 2013	88		$	31.01
Granted	69		33.65
Vested	(19	)	33.46
Canceled	(12	)	32.87
Balance, March 30, 2014	126		$	31.91	1.81	$	4,299
Vested and expected to vest at March 30, 2014	104		$	39.44	1.70	$	3,572

The aggregate intrinsic value in the tables above are before applicable income taxes and represent the amount recipients would have received if all stock options had been exercised or RSUs had been released on the last business day of the period indicated, based on the closing stock price of the Company's common stock on such date.

The total intrinsic value of stock options exercised during the quarter ended March 30, 2014 was $0.8 million. During the quarter ended March 30, 2014, the total fair value of stock options vested was $1.2 million. As of March 30, 2014, the Company had total unrecognized compensation costs related to unvested stock options and RSUs of $8.4 million, before income taxes. The Company expects to recognize this cost over a weighted average period of 2.4 years for the options and 3.4 years for the RSUs.