The Company administers a long-term incentive compensation plan that permits the granting of incentive awards in the form of stock options, restricted stock, restricted stock units, performance units, stock appreciation rights, or other stock-based awards. The terms of all awards issued under these plans are determined by the Compensation Committee of the Board of Directors.

The Amended and Restated 2015 Omnibus Incentive Plan (the “Plan”) permits the Company to grant to employees and directors various forms of incentive compensation. The principal purposes of this plan are to focus directors, officers, and other employees and consultants on business performance that creates shareholder value, to encourage innovative approaches to the business of the Company, and to encourage ownership of the Company’s stock. The Plan authorizes 7.5 million common share equivalents available for grant, where grants of full value awards (e.g., shares of restricted stock, restricted stock units and performance stock units) count as one share equivalent. The number of remaining share equivalents available for future issuance under the Plan was 4.2 million at March 31, 2020.

During the three months ended March 31, 2020 and 2019, the Company granted zero and 645,346 shares, respectively, of stock-based awards in the form of restricted stock units pursuant to and subject to the provisions of the Plan. The following table summarizes the activity related to restricted stock unit awards:

	For the Three Months Ended March 31,
	2020					2019
	Number of Shares			Weighted Average Fair Value per Unit at Award Date		Number of Shares			Weighted Average Fair Value per Unit at Award Date
Non-vested at beginning of period		1,229,863		$	19.97		273,354		$	26.49
Granted during the period		—			—		645,346			17.87
Vested during the period		(160,668	)		20.55		(44,501	)		26.50
Forfeited during the period		(56,429	)		20.20		(29,845	)		19.76
Non-vested at end of period		1,012,766		$	19.86		844,354		$	20.14

The restricted stock units granted include both time and performance-based components. Of the time-based restricted stock units granted and remaining at March 31, 2020:

While the grants specify a stated target number of units, the determination of the actual settlement in shares will be based in part on the achievement of certain financial performance measures of the Company. For the performance-based restricted stock units granted, these performance conditions will determine the actual units vesting and can be in the range of 25% to 200% of the units granted. These grants include rights as a shareholder in the form of dividend equivalents. Dividend equivalents for time vested restricted stock units will be paid on each dividend payment date for the Company; dividend equivalents for the performance vesting restricted stock will be accrued and paid on the vested number of shares once the performance is achieved and the shares are issued. The fair value of the restricted stock units was estimated based upon the fair value of the underlying shares on the date of the grant.

The Company recorded $1.1 million of equity-based compensation expense for the outstanding restricted stock units for the three months ended March 31, 2020, compared to $0.9 million for the three months ended March 31, 2019. The remaining expense related to unvested restricted stock units is $15.4 million as of March 31, 2020 and will be recognized over service periods ranging from 12 months to 42 months.

During the three months ended March 31, 2020 and 2019, the Company granted zero and 1,602,848 stock options, respectively, to certain executive officers. The options were granted at an exercise price equal to a 15% premium to the fair value of the common stock at the date of grant with a weighted-average exercise price of $20.43. The options vest over a three-year period and expire at the end of seven years. During the three months ended March 31, 2020, 534,283 stock options vested. The Company recorded $309 thousand of equity-based compensation expense for the outstanding stock options for the three months ended March 31, 2020, compared to $252 thousand for the three months ended March 31, 2019. The remaining expense related to non-vested stock option grants is $2.2 million at March 31, 2020 and will be recognized over the next 22 months.

The Company used the Black-Scholes option pricing model to estimate the fair value of the stock options. See Note 23 to the consolidated financial statements of our Annual Report on Form 10-K for the year ended December 31, 2019 for a description of the assumptions used for stock option awards issued during 2019.

On June 1, 2018, the Company commenced the 2018 Employee Stock Purchase Plan (“ESPP”) whereby employees may purchase the Company’s Class A common stock at a discount of 15% of the fair market value of a share of Class A common stock, defined as the closing price of Class A common stock on the NYSE for the first and last days of the purchase period (as defined in the ESPP). The total amount of the Company’s Class A common stock on which options may be granted under the ESPP shall not exceed 500,000 shares. Shares of Class A common stock subject to any unexercised portion of a terminated, canceled or expired option granted under the ESPP may again be used for options under the ESPP. No participating employee shall have any rights as a shareholder until the issuance of a stock certificate to the employee. There were 67,844 shares and 25,519 shares of Class A common stock purchased in the open market by the ESPP during the three months ended March 31, 2020 and 2019, respectively, which resulted in compensation expense of $14 thousand and $92 thousand for the three months ended March 31, 2020 and 2019, respectively.