Stockholders' Equity (Tables)

9 Months Ended

Sep. 30, 2018

The following table summarizes the Company’s stock option activity during the nine months ended September 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	(185	)	$0.88
Options canceled	(26	)	$1.54
Outstanding, September 30, 2018	5,515		$1.65	7.0	$113,383
Options exercisable at September 30, 2018	3,024		$0.91	6.5	$64,405
Options vested as of September 30, 2018 and expected to vest after September 30, 2018	4,734		$1.65	7.4	$98,034

Summary of Restricted Stock and Restricted Stock Unit Activity

Restricted stock award activity during the nine months ended September 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, September 30, 2018	115	$37.15

Restricted stock unit activity during the nine months ended September 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	454	$36.19
Units vested	—	$0.00
Units canceled	—	$0.00
Outstanding, September 30, 2018	454	$36.19

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 $20.7 million, which will be recognized during the remainder of 2018 and subsequent years as follows:



(in thousands)
2018	$	1,810
2019	6,802
2020	5,987
2021	4,364
2022	1,685
2023	7
	$	20,655