8. Equity Award Plans

In April 2006, the Company’s Board of Directors (the “Board”) adopted and the stockholders approved the 2006 Stock Option Plan (“2006 Plan”). The 2006 Plan provides for the grant of incentive stock options under the federal tax laws and non-statutory stock options. Only employees may receive incentive stock options, but non-statutory stock options may be granted to employees, non-employee directors and consultants. The stock options are exercisable at a price equal to the market value of the underlying shares of common stock on the date of the grant as determined by the Board. The term of options granted under the 2006 Plan may not exceed ten years. Certain options are eligible for exercise prior to vesting. Exercised but unvested shares of common stock are subject to repurchase by the Company at the initial exercise price. The proceeds from the shares of common stock subject to repurchase are classified as a liability and reclassified to equity as the shares vest. Under the 2006 Plan’s early exercise feature, the Company had the right to repurchase 5 and 18 shares of common stock as of June 30, 2016, and December 31, 2015, respectively. The Company records cash received from the exercise of unvested stock options as a long-term liability, as well as the fair value of vested outstanding options to non-employee consultants. As of June 30, 2016, and December 31, 2015, $46 and $249, respectively, has been recorded as a long-term liability on the accompanying unaudited condensed consolidated balance sheets.

In February 2013, the Board and stockholders approved the 2013 Equity Incentive Plan (“2013 Plan”), under which 4,500 shares of common stock were originally reserved for issuance. Additionally, all reserved and unissued shares under the 2006 Plan at the time the 2013 Plan became effective are eligible for issuance under the 2013 Plan. The 2013 Plan became effective on March 21, 2013, at which time the Company ceased to grant equity awards under the 2006 Plan. The 2013 Plan authorizes the award of stock options, restricted stock awards, stock appreciation rights, RSUs, performance awards and stock bonuses to the Company’s employees, directors, consultants, independent contractors and advisors. On January 1 of each of the first ten calendar years through 2023, the number of shares of common stock reserved under the 2013 Plan will automatically increase by an amount equal to 5% of the total outstanding shares as of immediately preceding December 31, or such lesser number of shares as determined by the Board. Pursuant to terms of the 2013 Plan, the shares available for issuance increased by approximately 1,878 shares of common stock on January 1, 2016.

Stock Options

A summary of stock option activity under the 2006 Plan and 2013 Plan is as follows:

	Options Outstanding
						Weighted
						Average
				Weighted		Remaining
				Average		Contractual		Aggregate
	Number of			Exercise		Term		Intrinsic
	Shares			Price Per Share		(in Years)		Value
Balances at December 31, 2015		5,960		$	7.58		7.85	$	957
Options granted		862			2.74		9.77
Options exercised		(77	)		2.45		—
Options forfeited and cancelled		(401	)		8.81		—
Balances at June 30, 2016		6,344		$	6.91		7.57	$	433
Options exercisable		3,272		$	7.79		6.31	$	349
Options vested		3,246		$	7.76		6.36	$	349
Options vested and expected to vest		6,086		$	6.96		7.51	$	428

RSUs

A summary of RSUs granted and unvested under the 2013 Plan is as follows:

	RSUs Outstanding
				Weighted Average
	Number of			Grant Date
	Shares			Fair Value Per Unit
Granted and unvested at December 31, 2015		1,221		$	9.36
RSUs granted		1,382			3.25
RSUs vested		(173	)		7.45
RSUs cancelled and withheld to cover taxes		(455	)		5.91
Granted and unvested at June 30, 2016		1,975		$	4.27

Employee Stock Purchase Plan

In February 2013, the Board and stockholders approved the 2013 Employee Stock Purchase Plan (“2013 ESPP”), under which 1,000 shares of common stock were originally reserved for issuance. The 2013 ESPP became effective on March 22, 2013. The 2013 ESPP provides generally for six-month purchase periods and the purchase price for shares of common stock purchased under the 2013 ESPP will be 85% of the lesser of the fair market value of the common stock on (i) the first trading day of the applicable offering period and (ii) the last trading day of each purchase period in the applicable offering period. On January 1 of each of the first 10 calendar years following the first offering date, the number of shares reserved under the 2013 ESPP will automatically increase by an amount equal to 1% of the total outstanding shares as of immediately preceding December 31, but not to exceed 700 shares. Pursuant to terms of the 2013 ESPP, the shares available for issuance increased by approximately 376 shares on January 1, 2016. During the three and six months ended June 30, 2016, 175 shares were issued under the 2013 ESPP. During the three and six months ended June 30, 2015, 105 shares were issued under the 2013 ESPP.