On May 9, 2019, the CBIZ shareholders approved CBIZ, Inc. 2019 Stock Omnibus Incentive Plan, which amended and restated the CBIZ, Inc. 2014 Stock Incentive Plan (as amended and restated, the “2019 Plan”). The 2019 Plan expires in 2029 and provides for the grant of restricted stock awards, stock options and performance awards. The terms and vesting schedules for the share-based awards vary by type and date of grant. A maximum of 9.6 million stock-based compensation awards may be granted. Shares subject to award under the 2019 Plan may be either authorized but unissued shares of our common stock or treasury shares. Compensation expense for stock-based awards recognized during the three and six months ended June 30, 2019 and 2018 was as follows (in thousands):

	Three Months Ended				Six Months Ended
	June 30,				June 30,
	2019		2018		2019		2018
Stock options	$	479	$	1,030	$	998	$	1,548
Restricted stock awards		1,153		1,383		2,082		2,302
Performance share units		285		—		319		—
Total stock-based compensation expense	$	1,917	$	2,413	$	3,399	$	3,850

Stock Options and Restricted Stock Awards – The following table presents our stock options and restricted stock award activity during the six months ended June 30, 2019 (in thousands, except per share data):

	Stock Options					Restricted Stock Awards
	Number of Options			Weighted Average Exercise Price Per Share		Number of Shares			Weighted Average Grant-Date Fair Value (1)
Outstanding at beginning of year		3,622		$	11.97		632		$	15.35
Granted		—		$	—		227		$	19.78
Exercised or released		(378	)	$	8.05		(282	)	$	13.76
Expired or canceled		—		$	—		—		$	—
Outstanding at June 30, 2019		3,244		$	12.43		577		$	17.88
Exercisable at June 30, 2019		2,287		$	10.65

Performance Share Units (“PSUs”) – PSUs are earned based on our financial performance over a contractual term of three years and the associated expense is recognized over that period based on the fair value of the award. A three-year cliff vesting schedule of the PSUs is dependent upon the Company’s performance relative to pre-established goals based on earnings per share target (weighted 70%) and total growth in revenue (weighted 30%). The fair value of PSUs is calculated using the market value of a share of our common stock on the date of grant. For performance achieved above specified levels, the recipient may earn additional shares of stock, not to exceed 200% of the number of PSUs initially granted.

The following table presents our PSU award activity during the six months ended June 30, 2019 (in thousands, except per share data):

	PSUs		Grant-Date Fair Value Per Unit
Outstanding at beginning of year		—	$	—
Granted		173	$	19.82
Vested		—	$	—
Adjustments for performance results		—	$	—
Expired or cancelled		—	$	—
Outstanding at June 30, 2019		173	$	19.82