The Company’s 2013 Stock Incentive Plan (as amended, the “2013 Equity Plan”) authorizes the issuance of various types of share-based awards to the Company’s employees, officers, directors, and other eligible participants. As of March 31, 2019, a total of 2,300,000 shares of the Company’s class A common stock were authorized for issuance under the 2013 Equity Plan. As of March 31, 2019, there were 573,750 shares of class A common stock reserved and available for future issuance under the 2013 Equity Plan.

During the three months ended March 31, 2019, stock options to purchase an aggregate of 30,000 shares of class A common stock were granted pursuant to the 2013 Equity Plan. As of March 31, 2019, there were options to purchase 1,459,983 shares of class A common stock outstanding under the 2013 Equity Plan.

The following table summarizes the Company’s stock option activity (in thousands, except per share data and years) for the three months ended March 31, 2019:

	Stock Options Outstanding
				Weighted Average		Aggregate		Weighted Average
				Exercise Price		Intrinsic		Remaining Contractual
	Shares			Per Share		Value		Term (Years)
Balance as of January 1, 2019		1,480		$	137.16
Granted		30		$	145.41
Exercised		(13	)	$	120.59	$	245
Forfeited/Expired		(37	)	$	140.98
Balance as of March 31, 2019		1,460		$	137.38
Exercisable as of March 31, 2019		814		$	137.00	$	12,929		5.9
Expected to vest as of March 31, 2019		646		$	137.85	$	7,628		8.9
Total		1,460		$	137.38	$	20,557		7.2

Stock options outstanding as of March 31, 2019 are comprised of the following range of exercise prices per share (in thousands, except per share data and years):

	Stock Options Outstanding at March 31, 2019
			Weighted Average		Weighted Average
			Exercise Price		Remaining Contractual
Range of Exercise Prices per Share	Shares		Per Share		Term (Years)
$119.02 - $140.00		1,154	$	126.44		7.3
$140.01 - $160.00		30	$	145.41		9.9
$160.01 - $180.00		113	$	167.75		5.9
$180.01 - $201.25		163	$	192.40		7.1
Total		1,460	$	137.38		7.2

An aggregate of 132,000 stock options with an aggregate fair value of $7.6 million vested during the three months ended March 31, 2019. The weighted average grant date fair value of stock option awards using the Black-Scholes pricing model was $54.85 and $52.44 for each share subject to a stock option granted during the three months ended March 31, 2019 and 2018, respectively, based on the following assumptions:

	Three months ended
	March 31,
	2019			2018
Expected term of options in years	6.3			6.3
Expected volatility		33.4	%	35.2% - 35.5%
Risk-free interest rate		2.5	%		2.7	%
Expected dividend yield		0.0	%		0.0	%

For the three months ended March 31, 2019 and 2018, the Company recognized approximately $3.0 million and $4.7 million, respectively, in share-based compensation expense from stock options granted under the 2013 Equity Plan. As of March 31, 2019, there was approximately $30.9 million of total unrecognized share-based compensation expense related to unvested stock options. The Company expects to recognize this remaining share-based compensation expense over a weighted average vesting period of approximately 2.9 years.

During the first quarter of 2019, the Company did not grant any “other stock-based awards” under the 2013 Equity Plan. For each of the three months ended March 31, 2019 and 2018, the Company did not recognize a material amount in share-based compensation expense from other stock-based awards. As of March 31, 2019, there was approximately $0.5 million of total unrecognized share-based compensation expense related to other stock-based awards. The Company expects to recognize this remaining share-based compensation expense over a weighted average vesting period of approximately 3.2 years, subject to additional fair value adjustments through the earlier of settlement or expiration.