Employee Benefit Plans and Stock-based Compensation (Tables)

12 Months Ended

Dec. 31, 2017

Employee Benefit Plans and Stock-based Compensation

The following table summarizes the stock option transactions for each of the years ended December 31, 2015, 2016 and 2017 (in thousands, except per share data):


				Weighted
				average
		Weighted-		Remaining
	Number of	average		Contractual	Aggregate
	Options	Exercise		Life	Intrinsic
Stock Options	Outstanding	Price		(in years)	Value

Balance as of January 1, 2015	3,198		3.12	6.95	$	1,247
Granted	866		2.19
Exercised	(119)		1.38
Canceled and expired	(166)		3.03
Balance as of December 31, 2015	3,779		2.97	6.26	$	764
Granted	624		4.92
Exercised	(555)		2.41
Canceled and expired	(554)		3.26
Balance as of December 31, 2016	3,294	$	3.38	7.23	$	5,301
Granted	184		8.99
Exercised	(762)		3.25
Canceled and expired	(50)		3.47
Balance as of December 31, 2017	2,666	$	3.81	6.87	$	13,149
Options vested as of December 31, 2017 and unvested options expected to vest, net of forfeitures	2,629	$	3.78	6.84	$	13,031
Options exercisable as of December 31, 2017	1,580	$	3.37	5.83	$	8,419

Summary of options outstanding and exercisable by exercise price ranges

The options outstanding and exercisable as of December 31, 2017 were in the following exercise price ranges (in thousands, except per share data):


									Options Vested and
					Options Outstanding as of				Exercisable as of
					December 31, 2017				December 31, 2017
								Weighted‑average
Range of						Weighted‑average		Remaining		Weighted‑Average
Exercise Price					Shares	Exercise Price		Contractual Life	Shares	Exercise Price
$	2.04	-	$	2.14	36	$	2.10	4.47	31	$	2.09
$	2.18	-	$	2.18	634	$	2.18	7.79	262	$	2.18
$	2.29	-	$	2.36	401	$	2.33	6.05	376	$	2.33
$	2.47	-	$	2.51	284	$	2.47	6.78	201	$	2.47
$	2.56	-	$	4.79	366	$	3.55	4.94	332	$	3.65
$	5.21	-	$	5.21	518	$	5.21	8.75	135	$	5.21
$	5.61	-	$	5.83	242	$	5.76	3.11	242	$	5.76
$	7.82	-	$	7.82	1	$	7.82	2.84	1	$	7.82
$	7.95	-	$	7.95	60	$	7.95	9.08	—	$	—
$	9.50	-	$	9.50	124	$	9.50	9.82	—	$	—
					2,666	$	3.81	6.87	1,580	$	$3.37

Summary of restricted stock awards activity


		Weighted-Average
		Grant Date
Stock Awards	Shares	Fair Value
Non-vested as of January 1, 2015	261	$	2.71
Granted	547	$	2.42
Vested	(215)	$	2.81
Forfeited	(47)	$	2.47
Non-vested as of December 31, 2015	546	$	2.39
Granted	136	$	4.66
Vested	(150)	$	2.34
Forfeited	(207)		2.55
Non-vested as of December 31, 2016	325	$	3.27
Granted	312	$	9.15
Vested	(157)	$	3.13
Forfeited	—	$	—
Non-vested as of December 31, 2017	480	$	7.13

Summary of common stock reserved for future issuance

The following number of shares of common stock were reserved and available for future issuance as of December 31, 2017 (in thousands, except per share data):


Options outstanding		2,666
Restricted stock awards outstanding		480
Stock available for future grant: 2015 Equity Incentive Plan		1,389
Total		4,535

Summary of compensation costs related to stock-based awards

The following table summarizes compensation costs related to our stock‑based compensation awards (in thousands, except per share data):


	Year Ended
	December 31,
	2017		2016		2015
Stock‑based compensation in the form of employee stock options and restricted stock, included in:
Cost of revenue	$	39	$	23	$	20
Selling, general and administrative		1,146		908		1,148
Research and development		220		165		181
Total stock-based compensation		1,405		1,096		1,349
Tax effect on stock-based compensation		—		—		—
Net effect on net income	$	1,405	$	1,096	$	1,349
Shares used in computing basic net income per share		37,444		32,139		32,183
Shares used in computing diluted net income per share		38,966		32,894		32,183
Effect on basic net income per share	$	(0.04)	$	(0.03)	$	(0.04)
Effect on diluted net income per share	$	(0.04)	$	(0.03)	$	(0.04)

Summary of weighted-average assumptions


	Year Ended
	December 31,
	2017		2016		2015
Expected term (in years)	5.8		4.0		3.9
Volatility	46.5	%	46.5	%	51.1	%
Expected dividend	—	%	—	%	—	%
Risk-free interest rate	2.10	%	1.47	%	1.75	%