10. Stock-Based Compensation Plans

The components of stock-based compensation expense for the three and six months ended June 30, 2018 and 2017 were as follows:


	Three months ended June 30,				Six months ended June 30,
	2018		2017		2018		2017
	(in thousands)				(in thousands)
2007 Stock Incentive Plan	$	1,660	$	1,194	$	2,565	$	2,059
Employee Stock Purchase Plan		—		6		20		15
Total Stock Compensation Expense	$	1,660	$	1,200	$	2,585	$	2,074

The 2007 Stock Incentive Plan (the “2007 Plan”) was adopted on May 24, 2007. Under this 2007 Plan, a total of 2,800,000 shares are authorized for stock based compensation available in the form of either restricted stock awards (“RSA’s”) or stock options. The RSA’s are subject to service-based vesting, typically between one and four years, where a specific period of continued employment must pass before an award vests. The expense associated with these awards is recognized on a straight-line basis over the respective vesting period, with forfeitures accounted for as they occur. For any vesting tranche of an award, the cumulative amount of compensation cost recognized is equal to the portion of the grant‑date fair value of the award tranche that is actually vested at that date.

As of June 30, 2018, the Company has granted 2,883,414 RSA’s under the 2007 Plan. Of this amount, 166,744 shares were cancelled and returned to the pool of shares which could be granted under the 2007 Plan resulting in a net number of 83,330 shares available for future issuance. The fair value of the restricted stock awards equaled the stock price at the grant date. There are no stock options outstanding under the 2007 Plan.

The 2018 Stock Incentive Plan (the “2018 Plan”) was adopted on May 24, 2018. Under this 2018 Plan, a total of 800,000 shares are authorized for stock based compensation, plus the number of shares remaining under the 2007 Plan and any future forfeited awards under the 2007 Plan, in the form of RSA’s. The RSA’s are subject to service-based vesting, typically between one and four years, where a specific period of continued employment must pass before an award vests. The expense associated with these awards is recognized on a straight-line basis over the respective vesting period, with forfeitures accounted for as they occur. For any vesting tranche of an award, the cumulative amount of compensation cost recognized is equal to the portion of the grant‑date fair value of the award tranche that is actually vested at that date.

As of June 30, 2018, the Company has not granted RSA’s under the 2018 Plan.

The following table summarizes restricted stock activity during the six months ended June 30, 2018:


		Shares
Restricted stock at December 31, 2017		328,122
Shares granted		267,454
Shares forfeited		—
Shares vested		(119,205)
Restricted stock at June 30, 2018		476,371

Under the Employee Stock Purchase Plan (“ESPP”), as amended and restated effective April 1, 2018, 325,000 shares of common stock have been reserved for issuance. Eligible employees may designate not more than 10% of their cash compensation to be deducted each pay period for the purchase of common stock under the Purchase Plan. Participants may purchase not more than 1,000 shares or $25,000 of common stock in any one calendar year. Each January 31 and July 31 shares of common stock are purchased with the employees’ payroll deductions from the immediately preceding six months at a price per share of 85% of the lesser of the market price of the common stock on the purchase date or the market price of the common stock on the date of entry into an offering period. In the first half of 2018 and 2017, respectively, 5,497 and 6,065 shares of common stock were issued under the ESPP. The Company issues new shares through its transfer agent upon employee stock purchase.