Stock-based Awards

Stock Options

A summary of the Company’s stock option activity for the nine months ended September 30, 2018 is as follows:



	Number of Options		Weighted-Average Exercise Price		Weighted-Average Remaining Contractual Life
					(in years)
Outstanding at December 31, 2017	16,714,216		$	12.46	7.7
Granted	1,492,481		9.69
Exercised	(2,126,522	)	9.12
Canceled/forfeited	(1,516,635	)	14.45
Outstanding at September 30, 2018	14,563,540		$	12.46	7.4

At September 30, 2018, total remaining stock-based compensation expense for unvested stock option awards was $38.6 million, which is expected to be recognized over a weighted-average period of 2.5 years. For the three months ended September 30, 2018 and 2017, the Company recorded stock-based compensation expense for stock option awards of $4.2 million and $5.3 million, respectively. For the nine months ended September 30, 2018 and 2017, the Company recorded stock-based compensation expense for stock option awards of $12.6 million and $12.3 million, respectively.

Restricted Stock Units

Activity in connection with restricted stock units is as follows for the nine months ended September 30, 2018:



	Number of Shares		Weighted- Average Grant Date Fair Value
Non-vested — December 31, 2017	4,284,438		$	11.99
Granted	3,376,074		10.00
Vested	(1,470,214	)	10.97
Canceled/forfeited	(759,197	)	11.04
Non-vested — September 30, 2018	5,431,101		$	11.16

At September 30, 2018, total remaining stock-based compensation expense for non-vested restricted stock units is $57.4 million, which is expected to be recognized over a weighted-average period of 2.9 years. The Company recorded $6.1 million and $4.6 million in stock-based compensation expense for restricted stock units for the three months ended September 30, 2018 and 2017, respectively. The Company recorded $15.7 million and $10.4 million in stock-based compensation expense for restricted stock units for the nine months ended September 30, 2018 and 2017, respectively.

Stock-based Compensation Cost

The Company recorded stock-based compensation cost relating to stock options and restricted stock units in the following categories on the accompanying consolidated statements of comprehensive loss (in thousands):



	Three Months Ended September 30,				Nine Months Ended September 30,
	2018		2017		2018		2017

Cost of revenue	$	469	$	339	$	1,210	$	775
Sales and marketing	3,852		3,358		10,522		7,263
Technology and development	2,829		2,598		7,880		5,496
General and administrative	3,097		3,613		8,704		9,127
Total stock-based compensation expense	10,247		9,908		28,316		22,661
Amount capitalized to internal software use	551		443		1,358		993
Total stock-based compensation cost	$	10,798	$	10,351	$	29,674	$	23,654