10. Stock Based Compensation

Stock Plans

Total share based compensation included in net income for the years ended December 29, 2017, December 30, 2016, and January 1, 2016 is as follows:

	Year Ended
	December 29,		December 30,		January 1,
	2017		2016		2016
Restricted stock units	$	7,801	$	7,550	$	6,776
Stock options and stock appreciation rights		—		—		2,658
Common stock subject to vesting requirements		2,515		1,215		927
	$	10,316	$	8,765	$	10,361

The number of shares available for future issuance under the Company's stock plans as of December 29, 2017 were 2,229,558. The Company issues new shares as they are required to be delivered under the plan.

Stock Options and SARs

The Company has granted stock options to employees and directors of the Company at exercise prices equal to the market value of the stock at the date of grant. The options generally vest ratably over four years, based on continued employment, with a maximum term of ten years. Stock option activity under the Company’s stock option plans for the year ended December 29, 2017 is summarized as follows:

	Option Shares			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term		Aggregate Intrinsic Value
Outstanding as of December 30, 2016		230,167		$	4.00
Exercised		(50,000	)		4.00
Forfeited or expired		—			—
Outstanding as of December 29, 2017		180,167		$	4.00		4.22	$	2,109,818
Exercisable at December 29, 2017		180,167		$	4.00		4.22	$	2,109,818

A summary of the Company’s stock option activity for the years ended December 30, 2016 and January 1, 2016 was as follows:

	December 30, 2016				January 1, 2016
	Option Shares		Weighted Average Exercise Price		Option Shares			Weighted Average Exercise Price
Outstanding at beginning of year		230,167	$	4.00		297,667			4.00
Exercised		—		—		(67,500	)		3.99
Forfeited or expired		—		—		—			—
Outstanding at end of year		230,167	$	4.00		230,167		$	4.00
Exercisable at end of year		230,167	$	4.00		90,167		$	4.00

10. Stock Based Compensation (continued)

The fair value of the SARs and stock options is estimated using the Black-Scholes option pricing valuation model. The determination of fair value is affected by the Company's stock price, expected stock price volatility, expected term of the award and the risk-free rate of interest.

Other information pertaining to stock option activity during the years ended December 29, 2017, December 30, 2016, and January 1, 2016 was as follows (in thousands):

	Year Ended
	December 29, 2017		December 30, 2016		January 1, 2016
Total intrinsic value of stock options exercised	$	803	$	—	$	660

On February 8, 2012, the Compensation Committee approved the fiscal year 2012 through 2015 equity compensation target for the Chief Executive Officer and Chief Operating Officer. Under this target, a single performance-based option grant was made to the Company’s Chief Executive Officer and the Chief Operating Officer of 1,912,500 options and 1,004,063 options, respectively, totaling 2,916,563 options, each with an exercise price of $4.00 and a fair value of $1.31. One -half of the options vest upon the achievement of at least 50% growth of pro forma earnings per share and the remaining half vest upon the achievement of at least 50% pro forma EBITDA growth. Pro forma EBITDA is defined as pro forma earnings (which specifically excludes non-cash stock compensation expense, intangible asset amortization expense, acquisition-related charges and gains, restructuring charges and assumes a normalized long-term cash rate of 30%) before interest, taxes and depreciation. Each metric can be achieved at any time during the six -year term of the award based on a trailing twelve-month period measured quarterly. The grants will expire if neither target is achieved during the six-year term. The base year for the performance calculation is fiscal 2011 for both pro forma earnings per share and pro forma EBITDA performance targets.

In March of 2013, the performance-based stock option grants were surrendered by the Company’s Chief Executive Officer and Chief Operating Officer and replaced with SARs, totaling 2,916,563, equal in number to the number of options granted to each of them in 2012. The terms and conditions and the specific performance targets that must be achieved in order for the SAR s to vest are the same as those of the surrendered options, with the exception that the SARs will be settled in cash, stock or any combination thereof, at the Company’s discretion.

The SARs related to the pro forma EPS target were earned and vested in the first quarter of 2015 with the Audit Committee’s approval of the Company’s 2014 financial statements and the SARs related to the pro forma EBITDA target were earned and vested in the first quarter of 2016 with the Audit Committee’s approval of the Company’s 2015 financial statements. As of December 29, 2017, no SARs had been exercised.

SAR activity for the year ended December 29, 2017 was as follows:

	Number of SARs		Weighted Average Exercise Price		Weighted Average Fair Value
Outstanding as of December 30, 2016		2,916,563	$	4.00		1.31
Expired		—		—		—
Outstanding as of December 29, 2017		2,916,563	$	4.00	$	1.31
Exercisable at December 29, 2017		2,916,563	$	4.00	$	1.31

The following assumptions were used to determine the fair value of the SARs granted to employees:

Expected volatility		43	%
Risk-free rate	0.35% -1.00%
Expected term (in years)	2-6

10. Stock Based Compensation (continued)

As of December 29, 2017, 100% of total outstanding options and SARs were performance-based. The Company did not record any compensation expense in 2017 related to the options and SARs, but did record $2.7 million of compensation expense in 2015 related to these options and SARs. As of January 1, 2016, all stock compensation expense related to the outstanding options and SARs had been expensed.

Restricted Stock Units

Under the stock plans, participants may be granted restricted stock units, each of which represents a conditional right to receive a common share in the future. The restricted stock units granted under this plan generally vest over one of the following vesting schedules: (1) a four -year period, with 50% vesting on the second anniversary and 25% of the shares vesting on the third and fourth anniversaries of the grant date, (2) a four -year period, with 25% vesting on the first, second, third and fourth anniversary, or (3) a three -year period with 33% vesting on the first, second and third anniversary. Upon vesting, the restricted stock units will convert into an equivalent number of shares of common stock. The amount of expense relating to the restricted stock units is based on the closing market price of the Company’s common stock on the date of grant and is amortized on a straight-line basis over the applicable requisite service period. Restricted stock unit activity for the year ended December 29, 2017, was as follows:

	Number of Restricted Stock Units			Weighted Average Grant-Date Fair Value
Nonvested balance as of December 30, 2016		1,779,480		$	9.02
Granted		674,592			16.60
Vested		(862,731	)		7.77
Forfeited		(71,703	)		13.24
Nonvested balance as of December 29, 2017		1,519,638		$	12.96

The Company recorded restricted stock units based compensation expense of $7.8 million, $7.6 million and $6.8 million in 2017, 2016, and 2015, respectively, which is included in stock compensation expense, based on the vesting provisions of the restricted stock units and the fair market value of the stock on the grant date. As of December 29, 2017, there was $9.1 million of total restricted stock unit compensation expense related to the nonvested awards not yet recognized, which is expected to be recognized over a weighted average period of 1.9 years. The Company accounts for certain restricted stock units under liability accounting as a result of the fixed monetary amount and a variable number of shares that will be issued. See Note 5 for further details.

Common Stock Subject to Vesting Requirements

Shares of common stock subject to vesting requirements were issued to employees of acquired companies. These shares vest over a period of up to four years. Compensation was based on the market value of the Company’s common stock at the time of grant and is recognized on a straight-line basis. The activity for common stock subject to vesting requirement s for the year ended December 29, 2017 was as follows:

	Number of Shares of Common Stock Subject to Vesting Requirements			Weighted Average Grant-Date Fair Value
Nonvested balance as of December 30, 2016		505,060		$	9.00
Granted		182,279			19.82
Vested		(248,587	)		9.11
Forfeited		(7,728	)		8.99
Nonvested balance as of December 29, 2017		431,024		$	13.52

Common stock subject to vesting requirements of $3.6 million and $4.6 million was issued in 2017 and 2015, respectively, in relation to the equity portion of the Jibe acquisition closing consideration and the Technolab earn-out consideration, respectively. These shares are subject to a four year vesting period.

The Company recorded compensation expense of $2.5 million, $1.2 million and $0.9 million, during the years ended December 29, 2017, December 30, 2016, and January 1, 2016, respectively, related to common stock subject to vesting requirements.

10. Stock Based Compensation (continued)

As of December 29, 2017, there was $ 4.2 million of total stock based compensation expense related to common stock granted subject to vesting requirements not yet recognized, which is expected to be recognized over a weighted average period of 2.7 years.