8. Equity-Based Compensation

General

The Company has granted options to purchase the Company’s common stock under its 2014 GYP Holdings I Corp. Stock Option Plan. The stock options granted under this plan vest over a four-year period and have a 10‑year term. In October 2017, the stockholders of the Company approved the GMS Inc. Equity Incentive Plan (the “Equity Incentive Plan”). Future grants will be made from the Equity Incentive Plan. The Equity Incentive Plan is administered by a committee of the Board of Directors, which determines the terms of the awards granted. Under the Equity Incentive Plan, the committee may grant various forms of equity-based incentive compensation, including stock options, stock appreciation rights, restricted stock, restricted stock units and performance awards, among others. The Company’s Equity Incentive Plan provides for the issuance of a maximum of 2.5 million shares, of which approximately 2.4 million shares were still available for grant as of July 31, 2018. The Company intends to use authorized and unissued shares to satisfy share award exercises.

The Company measures compensation cost for all share‑based awards at fair value on the grant date (or measurement date if different) and recognizes compensation expense, net of estimated forfeitures, over the requisite service period for awards expected to vest. The Company estimates the fair value of stock options using the Black-Scholes valuation model, and determines the fair value of restricted stock units based on the quoted price of GMS’s common stock on the date of grant. The Company estimates forfeitures based on historical analysis of actual forfeitures and employee turnover. Actual forfeitures are recorded when incurred and estimated forfeitures are reviewed and adjusted at least annually.

Equity-based compensation expense related to stock options and restricted stock units was $0.4 million and $0.5 million during the three months ended July 31, 2018 and 2017, respectively, and is included in selling, general and administrative expenses in the Condensed Consolidated Statements of Operations and Comprehensive Income.

Stock Option Awards

The following table presents stock option activity for the three months ended July 31, 2018:


				Weighted
		Weighted		Average
		Average		Remaining	Aggregate
	Number of	Exercise		Contractual	Intrinsic
	Options	Price		Life (years)	Value
	(shares and dollars in thousands)
Outstanding as of April 30, 2018	1,952	$	14.37	6.52	$	33,209
Options granted	—		—
Options exercised	(35)		12.31
Options forfeited	(2)		37.49
Options expired	—		—
Outstanding as of July 31, 2018	1,915	$	14.39	6.36	$	25,046
Exercisable as of July 31, 2018	1,701	$	13.04	6.15	$	23,907
Vested and expected to vest as of July 31, 2018	1,910	$	14.35	6.35	$	25,030

The aggregate intrinsic value represents the value of the Company’s closing stock price on the last trading day of the period in excess of the weighted average exercise price multiplied by the number of options outstanding, exercisable or expected to vest. Options expected to vest are unvested shares net of expected forfeitures. The total intrinsic value of options exercised during the three months ended July 31, 2018 was $0.5 million. There were no stock option exercises during the three months ended July 31, 2017. As of July 31, 2018, there was $0.9 million of total unrecognized compensation cost related to stock options. That cost is expected to be recognized over a weighted-average period of 2.0 years.

There were no stock options granted during the three months ended July 31, 2018 and 2017.

Restricted Stock Units

The following table presents restricted stock unit activity for the three months ended July 31, 2018:


		Weighted
	Number of	Average
	Restricted	Exercise
	Stock Units	Price
Outstanding as of April 30, 2018	21,766	$	37.49
Granted	—		—
Vested	(655)		37.49
Forfeited	—		—
Outstanding as of July 31, 2018	21,111	$	37.49

As of July 31, 2018, there was $0.6 million of total unrecognized compensation cost related to nonvested restricted stock units. That cost is expected to be recognized over a weighted-average period of 2.4 years.