The Company’s 2008 Equity Compensation Plan, as amended and restated (the “Plan”) allows for grants in the form of incentive stock options, nonqualified stock options, stock units, stock awards, stock appreciation rights, and other stock-based awards. All of the Company’s officers, directors, employees, consultants and advisors are eligible to receive grants under the Plan. The maximum number of shares authorized for issuance under the Plan is 32,200 and the maximum number of shares of stock that may be granted to any one employee for qualified performance-based compensation during a calendar year is 4,000 shares. Options to purchase shares of common stock are granted at exercise prices not less than 100% of fair market value on the dates of grant. The term of each option is ten years and the options typically vest in quarterly installments over a three-year period with a minimum vesting period of one year. As of March 31, 2019, the Plan had approximately 3,148 shares available for grant. Stock option exercises are satisfied through the issuance of new shares.

The following is a summary of stock option activity under the Plan as of and for the three months ended March 31, 2019:

						Weighted
				Weighted		Average
				Average		Remaining		Aggregate
	Number of			Exercise		Contractual		Intrinsic
	Shares			Price		Term (Years)		Value
Outstanding at December 31, 2018		14,079		$	2.19
Granted		20			3.72
Exercised		(212	)		1.65
Cancelled/Forfeited		(30	)		2.95
Outstanding at March 31, 2019		13,857			2.20		6.4	$	12,048
Exercisable at March 31, 2019		11,025		$	2.09		5.8	$	10,853

During the three months ended March 31, 2019, stock option exercises resulted in cash proceeds to the Company of $350 and the issuance of 212 shares of common stock. Stock option exercises resulted in proceeds of $28 and the issuance of 32 shares of common stock in the three months ended March 31, 2018. The Company recognized $908 and $661 of compensation expense related to stock options for the three months ended March 31, 2019 and 2018, respectively.

The Company’s Board of Directors has approved a long-term incentive program (“LTIP”) for the benefit of the Company’s senior executives. Pursuant to the LTIP, the Company’s senior executives have been awarded stock options, restricted stock units (“RSUs”) and performance stock units (“PSUs”) with targeted values based on values granted to similarly situated senior executives in the Company’s peer group. The stock options have a ten-year term, have an exercise price equal to the closing price of the Company’s common stock on the date of grant, vest in quarterly installments over three years, were otherwise granted on the same standard terms and conditions as other stock options granted pursuant to the Plan and are included in the stock options table above. The RSUs vest in three equal annual installments. The PSU awards made to senior executives vest and convert into shares of the Company’s common stock based on the Company’s attainment of certain performance goals as established by the Company’s Board of Directors over a performance period, which is typically three years.

The non-vested PSU awards and RSU awards granted under the long-term incentive program are summarized in the following table:

	Performance Stock Units					Restricted Stock Units
	Number of Shares			Weighted Average Grant Date Fair Value		Number of Shares		Weighted Average Grant Date Fair Value
Outstanding at December 31, 2018		1,842		$	2.41		1,226	$	2.44
Granted		—			—		—		—
Vested/settled		(415	)		1.18		—		—
Forfeited/expired		(178	)		1.12		—		—
Outstanding at March 31, 2019		1,249		$	3.01		1,226	$	2.44

In connection with PSU awards, the Company recognized compensation expense of $127 and $79 for the three months ended March 31, 2019 and 2018, respectively. Compensation expense recognized in connection with RSU awards was $331 and $245 for the three months ended March 31, 2019 and 2018, respectively.

The LTIP awards that vested during the three months ended March 31, 2019 and 2018 were net-share settled such that the Company withheld shares with a value equivalent to the employees’ tax obligations for applicable income and other employment taxes, and remitted the cash to the appropriate taxing authorities. The Company withheld 127 and 59 shares during the three months ended March 31, 2019 and 2018, respectively, to satisfy tax obligations, which was determined based on the fair value of the shares on their vesting date equal to the Company’s closing stock price on such date. Total payments for the employees’ tax obligations to the taxing authorities were $408 and $130 for the three months ended March 31, 2019 and 2018, respectively, and are reflected as a cash outflow from financing activities within the consolidated statements of cash flows. Net-share settlements have the effect of share repurchases by the Company as they reduce the number of shares that would have otherwise been issued as a result of the vesting.