Stockholders' Equity (Tables)

6 Months Ended

Jun. 30, 2018

The following table summarizes the Company’s stock option activity during the six months ended June 30, 2018:



(in thousands)	Number of shares		Weighted average exercise price	Weighted average remaining contractual term (years)	Aggregate intrinsic value
Outstanding, December 31, 2017	5,369		$1.09	7.4	$29,863
Options granted	357		$9.71
Options exercised	(141	)	$0.88
Options canceled	(18	)	$1.50
Outstanding, June 30, 2018	5,567		$1.65	7.2	$174,883
Options exercisable at June 30, 2018	2,707		$0.88	6.6	$87,093
Options vested as of June 30, 2018 and expected to vest after June 30, 2018	4,624		$1.65	7.7	$145,939

Summary of Restricted Stock and Restricted Stock Unit Activity

Restricted stock award activity during the six months ended June 30, 2018 was as follows:



(in thousands)	Number of restricted stock awards	Weighted average grant date fair value
Outstanding, December 31, 2017	—	$0.00
Awards granted	115	$37.15
Awards vested	—	$0.00
Awards canceled	—	$0.00
Outstanding, June 30, 2018	115	$37.15

Restricted stock unit activity during the six months ended June 30, 2018 was as follows:



(in thousands)	Number of restricted stock units	Weighted average grant date fair value
Outstanding, December 31, 2017	—	$0.00
Units granted	443	$36.28
Units vested	—	$0.00
Units canceled	—	$0.00
Outstanding, June 30, 2018	443	$36.28

Total Compensation Cost Related to Nonvested Awards Not Yet Recognized

Total compensation cost related to nonvested options, restricted stock units and restricted stock awards not yet recognized is $22.8 million, which will be recognized during the remainder of 2018 and subsequent years as follows:



(in thousands)
2018	$	3,683
2019	7,023
2020	6,051
2021	4,344
2022	1,652
2023	9
	$	22,762