11. Equity-Based Compensation

General

The Company has a 2014 GYP Holdings I Corp. Stock Option Plan (the "Plan") that provides for granting of stock options and other equity awards. The Plan authorizes 3,591,422 shares of common stock for issuance. The stock options vest over a four year period and have a 10-year term. The plan is designed to motivate and retain individuals who are responsible for the attainment of our primary long-term performance goals. The plan provides a means whereby our employees and directors develop a sense of ownership and personal involvement in our development and financial success and encourage them to devote their best efforts to our business. The Company accounts for share-based awards in accordance with ASC 718. ASC 718 requires measurement of compensation cost for all share-based awards at fair value on the grant date (or measurement date if different) and recognition of compensation expense, net of estimated forfeitures, over the requisite service period for awards expected to vest.

Stock Option Awards

We utilize the Black-Scholes option-pricing model to estimate the grant-date fair value of all stock options granted during fiscal year 2017. The Black-Scholes option-pricing model requires the use of weighted average assumptions for estimated expected volatility, estimated expected term of stock options, risk-free rate, estimated expected dividend yield, and the fair value of the underlying common stock at the date of grant. Due to the recent date of our initial public offering as discussed in Note 1, "Basis of Presentation, Business and Summary of Significant Accounting Policies," we do not have sufficient history to estimate the expected volatility of our common stock price. Thus, expected volatility has been based on the average volatility of peer public entities that are similar in size and industry. We estimate the expected term of all stock options based on previous history of exercises. The risk-free rate is based on the U.S. Treasury yield curve in effect at the time of grant for the expected term of the stock option. The expected dividend yield is 0% as we have not declared any common stock dividends to date and do not expect to declare common stock dividends in the near future. The fair value of the underlying common stock at the date of grant was determined based on the value of our common stock at the date of grant. We estimate forfeitures based on our historical analysis of actual stock option forfeitures and employee turnover. Actual forfeitures are recorded when incurred and estimated forfeitures are reviewed and adjusted at least annually. The weighted average assumptions used in the Black-Scholes option-pricing model for the year ended April 30, 2017 are set forth below:

	April 30, 2017
Volatility		40.68	%
Expected life (years)		6.0
Risk-free interest rate		1.55	%
Dividend yield		—	%

In fiscal 2017, the Company accounted for 180,539 stock option awards issued to employees that vest based on service only. The weighted average grant date fair value of each stock option was $9.68. All of these awards vest over a four-year period. Additionally, all these options could vest earlier in the event of a change in control, merger or other acquisition.

The Company did not issue any stock option awards in fiscal 2016.

In fiscal 2015, the Company accounted for 2,824,050 stock option awards issued to employees that vest based on service only. The weighted average grant date fair value of each stock option was $4.73. All of these options could vest earlier in the event of a change in control, merger or other acquisition.

The aggregate fair value of options outstanding, including vested and unvested, at April 30, 2017 and April 30, 2016 was $10,753 and $9,131, respectively. The aggregate fair value of options vested at April 30, 2017 and April 30, 2016 was $5,653 and $3,005, respectively.

The expense related to the vesting of stock options is recorded on an accelerated basis over the requisite service period of each separate vesting tranche. Share-based compensation expense related to stock option awards was $2,368, $2,697 and $6,455 for the years ended April 30, 2017, 2016 and 2015, respectively, and was included as a component of "Selling, general and administrative" expenses in our Consolidated Statements of Operations and Comprehensive Income (Loss). As of April 30, 2017 and 2016, the unrecognized compensation expense related to stock option awards was $1,869 and $2,344, respectively, with a remaining vested life of 1.52 years and 2.0 years, respectively.

A summary of stock option activity for the years ended April 30, 2017 and 2016 follows:

	Number of options		Weighted average exercise price		Weighted average remaining contractual life (years)		Aggregate intrinsic value
Outstanding at May 1, 2015		2,824,050	$	12.53

Options granted		—		—
Options exercised		529,595		12.31
Options forfeited		359,349		12.31
Options expired		—		—

Outstanding at April 30, 2016		1,935,106	$	12.37		7.98	$	16,700

Options granted		180,539		23.65
Options exercised		28,000		12.31
Options forfeited		—		—
Options expired		—		—

Outstanding at April 30, 2017		2,087,645	$	13.49		7.23	$	47,336

Exercisable at April 30, 2017		1,211,044		12.48		7.02	$	28,681

Expected to vest after April 30, 2017		876,601	$	14.88		7.52	$	18,655

Aggregate intrinsic value represents the fair value of the underlying common stock at the date of grant, in excess of the weighted average exercise price multiplied by the number of options outstanding or exercisable. Options expected to vest are unvested shares net of expected forfeitures.

As of April 30, 2017 and 2016, the aggregate intrinsic value of unvested options outstanding was $18,655 and $11,120, respectively, and the aggregate intrinsic value of options vested was $28,681 and $5,580, respectively. The total intrinsic value of stock option awards exercised was approximately $580 and $8,892 during the fiscal years ended April 30, 2017 and 2016, respectively.