8. Stock-Based Compensation

Stock Incentive Plans

The Company has two equity incentive plans: the 2006 Stock Plan (“2006 Plan”) and the 2015 Omnibus Equity Incentive Plan (“2015 Plan”).

In 2006, the Company adopted the 2006 Plan, which provided for the granting of stock options to executives, employees, and other service providers under terms and provisions established by the Board of Directors. The Company granted non-statutory stock options (“NSOs”) under the 2006 Plan until May 2015, when it was terminated as to future awards, although it continues to govern the terms of options that remain outstanding and were issued under the 2006 Plan. The 2015 Plan became effective upon the Company’s IPO in May 2015 and all shares that were reserved, but not issued, under the 2006 Plan were assumed by the 2015 Plan. Upon effectiveness, the 2015 Plan had 3,087,729 shares of common stock reserved for future issuance, which included 212,729 shares under the 2006 Plan that were transferred to and assumed by the 2015 Plan. The 2015 Plan provides for automatic annual increases in shares available for grant. In addition, shares subject to awards under the 2006 Plan that are forfeited or canceled will be added to the 2015 Plan. The 2015 Plan provides for the grant of incentive stock options (“ISOs”), NSOs, restricted stock awards, stock units, stock appreciation rights, and other forms of equity compensation, all of which may be granted to employees, officers, non-employee directors, and consultants. The ISOs and NSOs will be granted at a price per share not less than the fair value at the date of grant. Options granted generally vest over a four-year period, with 25% vesting at the end of one year and the remaining vesting monthly thereafter. Options granted, once vested, are generally exercisable for up to 10 years after grant.

As of March 31, 2017, a total of 7,071,728 shares of common stock were reserved for issuance under the 2015 Plan, of which 5,458,292 shares of common stock are available for future grant. As of March 31, 2017, a total of 2,766,803 and 1,613,496 options are outstanding under the 2006 and 2015 Plans, respectively.

A summary of activity under the stock incentive plans is as follows (in thousands, except share data and price per share):

	Shares Subject to Outstanding Options			Weighted- Average Exercise Price Per Share		Aggregate Intrinsic Value
Outstanding — Balance at December 31, 2016		4,578,782		$	4.38	$	—
Options granted		—		N/A
Options exercised		—		N/A
Options cancelled and forfeited		(198,483	)		3.36
Outstanding — Balance at March 31, 2017		4,380,299		$	4.42	$	—
Vested and expected to vest — March 31, 2017		4,346,958		$	4.41	$	—
Exercisable —March 31, 2017		2,713,195		$	3.65	$	—

As of March 31, 2017, there was $1.6 million of unrecognized compensation cost related to unvested stock-based compensation grants that will be recognized over the weighted-average remaining recognition period of 2.87 years.

There were no options granted during both three months ended March 31, 2017 and 2016.

Employee Stock Purchase Plan

The Company’s 2015 Employee Stock Purchase Plan (“ESPP”) became effective on May 14, 2015. The ESPP allows eligible employees to purchase shares of the Company’s common stock at a discount of up to 15% of their eligible compensation through payroll deductions, subject to any plan limitations. After the first offering period, which began on May 14, 2015 and ended on February 1, 2016, the ESPP provides for six-month offering periods, and at the end of each offering period, employees are able to purchase shares at 85% of the lower of the fair market value of the Company’s common stock on the first trading day of the offering period or on the last trading day of the offering period. As of March 31, 2017, the number of shares of common stock reserved for future issuance under the ESPP is 1,403,627. The ESPP provides for automatic annual increases in the shares available for purchase beginning on January 1, 2016. As of March 31, 2017, 96,373 shares had been issued under the ESPP. The Company recorded $4,000 and $30,000 of compensation expense for the three months ended March 31, 2017 and 2016, respectively.

Warrants

On December 2013, the Company issued warrants to Mahyco International to purchase 75,666 shares of common stock, exercisable as of the issuance date, at an exercise price of $16.52 per share.

In connection with the Series D preferred stock financing in the first half of 2014, the Company issued warrants, exercisable as of the issuance date, to the Series D preferred stock investors to purchase an aggregate of 1,227,783 shares of common stock at an exercise price of $18.16 per share and to the placement agent to purchase 33,445 shares of common stock at $13.45.

All warrants expire five years from the warrants’ issuance date.