Stock-Based Compensation

Stock-based compensation is measured at the grant date, based on the calculated fair value of the award, and is recognized as expense over the requisite employee service period (generally the vesting period of the grant). The Company recognized $1.3 million in stock compensation expense for the twenty-six weeks ended June 30, 2018, with a corresponding increase to additional paid-in-capital. Stock compensation expense is included in SG&A in the Consolidated Statements of Operations.

Stock Options

The following table summarizes stock option activity (in thousands, except per share data):



	Stock Options		Weighted Average Exercise Price		Aggregate Intrinsic Value		Weighted Average Remaining Term
Outstanding - December 30, 2017	420		$	5.45	$	14,068	5.7
Options granted	2		44.03
Options exercised	(136	)	3.34
Options canceled	(27	)	6.68
Outstanding - June 30, 2018	259		$	5.88	$	11,963	5.3

The total grant-date fair value of stock options vested during the twenty-six weeks ended June 30, 2018 was $0.5 million. The total intrinsic value of stock options exercised during the twenty-six weeks ended June 30, 2018 was $6.3 million. As of June 30, 2018, total unrecognized compensation expense related to unvested stock options was $0.6 million, which is expected to be recognized over a weighted-average period of 1.4 years.

Restricted Stock Units and Performance Stock Units

The following table summarizes activity related to restricted stock units and performance stock units (in thousands, except per share data):



	Restricted Stock Units		Weighted Average Grant Date Fair Value		Performance Stock Units		Weighted Average Grant Date Fair Value
Outstanding - December 30, 2017	94		$	27.11	86		$	27.63
Units granted	59		44.25		54		44.27
Units vested	(28	)	26.74		(14	)	26.25
Units canceled	(12	)	27.83		(7	)	26.30
Outstanding - June 30, 2018	113		$	36.07	119		$	38.31

The fair value of restricted stock units and performance stock units is based on the closing market price of the stock on the date of grant. The restricted stock units granted during the twenty-six weeks ended June 30, 2018 vest over a three year service period. As of June 30, 2018, total unrecognized compensation expense related to unvested restricted stock units was $3.5 million, which is expected to be recognized over a weighted-average period of 2.2 years.

The performance stock units vest based on the outcome of certain performance criteria. For performance stock units granted during the twenty-six weeks ended June 30, 2018, the amount of units that can be earned range from 0% to 100% of the number of performance awards granted, based on the achievement of certain adjusted EBITDA targets, as defined by the applicable award agreement, over a performance period of one to three years. The compensation expense related to the performance stock units is recognized over the vesting period when the achievement of the performance conditions become probable. During the twenty-six weeks ended June 30, 2018, there was a modification to certain awards resulting in additional compensation expense of $0.9 million over the remaining term of the awards.

As of June 30, 2018, total unrecognized compensation expense related to unvested performance stock units was $4.1 million, which is expected to be recognized over a weighted-average period of 2.0 years.

Restricted Stock Awards

The fair value of the non-vested restricted stock awards is based on the closing price on the date of grant. As of June 30, 2018, total unrecognized compensation expense related to unvested restricted stock awards was $0.5 million, which will be recognized over a weighted average period of approximately 2.1 years.