STOCK-BASED COMPENSATION

We record stock-based compensation expense for restricted and unrestricted stock awards, performance share units, stock options, and shares purchased under an employee stock purchase plan.

Stock-based compensation expense was as follows (in millions):



	Thirteen weeks ended
	March 28, 2014		March 29, 2013
Restricted and unrestricted stock and performance share units	$	2.7	$	2.8
Stock options	0.1		—
Employee stock purchase plan	0.1		0.1
Total stock-based compensation	$	2.9	$	2.9

Our 2005 Long-Term Equity Incentive Plan, as amended and restated effective May 2013 ("Incentive Plan"), provides for the issuance or delivery of up to 7.95 million shares of our common stock over the full term of the Incentive Plan.

Restricted and unrestricted stock and performance share units

Under the Incentive Plan, restricted stock is granted to executive officers and key employees and vests annually over three or four years. Unrestricted stock granted to our directors vests immediately. Restricted and unrestricted stock-based compensation expense is calculated based on the grant-date market value. We recognize compensation expense on a straight-line basis over the vesting period, net of estimated forfeitures.

Performance share units have been granted to executive officers and certain key employees. Vesting of the performance share units is contingent upon the achievement of revenue and/or profitability growth goals at the end of each three year performance period. Each performance share unit is equivalent to one share of common stock. Compensation expense is calculated based on the grant-date market value of our stock and is recognized ratably over the performance period for the performance share units which are expected to vest. Our estimate of the performance units expected to vest is reviewed and adjusted as appropriate each quarter.

Restricted and unrestricted stock and performance share units activity for the thirteen weeks ended March 28, 2014 was as follows (shares in thousands):



	Shares		Weighted- average grant-date price
Non-vested at beginning of period	1,544		$	16.66
Granted	350		$	25.20
Vested	(357	)	$	17.77
Forfeited	(11	)	$	17.81
Non-vested at the end of the period	1,526		$	18.25

As of March 28, 2014, total unrecognized stock-based compensation expense related to non-vested restricted stock was approximately $11.1 million, of which $9.8 million is estimated to be recognized over a weighted average period of 1.86 years through 2017. As of March 28, 2014, total unrecognized stock-based compensation expense related to performance share units, assuming achievement of maximum financial goals, was approximately $11.1 million, of which $4.6 million is currently estimated to be recognized over a weighted average period of 2.07 years through 2016.

Stock options

Our Incentive Plan provides for both nonqualified stock options and incentive stock options (collectively, “stock options”) for directors, officers, and certain employees. We issue new shares of common stock upon exercise of stock options. All of our stock options are vested and expire if not exercised within seven to ten years from the date of grant.

Stock option activity for the thirteen weeks ended March 28, 2014 was as follows (shares in thousands):



	Shares		Weighted Average Exercise Price		Weighted Average Remaining Contractual Life	Aggregate Intrinsic Value (in millions)
Outstanding, December 27, 2013	74		$	14.99
Granted	7		$	25.26
Exercised	(17	)	$	15.17
Expired/Forfeited	(1	)	$	18.98
Outstanding, March 28, 2014	63		$	15.95	2.14	$	0.8
Exercisable, March 28, 2014	63		$	15.95	2.14	$	0.8

The aggregate intrinsic value in the table above is the amount by which the market value of the underlying stock exceeded the exercise price of outstanding options, before applicable income taxes and represents the amount optionees would have realized if all in-the-money options had been exercised on the last business day of the period indicated.

There were no stock options granted during fiscal 2013. A summary of the weighted average assumptions and results for stock options granted during the thirteen weeks ended March 28, 2014 is as follows:



	March 28, 2014
Expected life (in years)	3.72
Expected volatility	42.8		%
Risk-free interest rate	0.7		%
Expected dividend yield	—		%
Weighted average fair value of options granted during the period	$	8.31

Employee stock purchase plan

Our Employee Stock Purchase Plan (“ESPP”) reserves for purchase 1.0 million shares of common stock. The plan allows eligible employees to contribute up to 10% of their earnings toward the monthly purchase of the Company's common stock. The employee's purchase price is the lesser of 85% of the fair market value of shares on either the first day or the last day of each month. We consider our ESPP to be a component of our stock-based compensation and accordingly we recognize compensation expense over the requisite service period for stock purchases made under the plan. The requisite service period begins on the enrollment date and ends on the purchase date, the duration of which is one month.

During the thirteen weeks ended March 28, 2014 and March 29, 2013, participants purchased 17,000 and 24,000 shares from the plan, respectively, for cash proceeds of $0.3 million for each period.