Stockholders’ Equity

Common Stock

In May 2017, the Company completed a public offering of 5,980,000 shares of its common stock at a public offering price of $5.50 per share. The shares were registered pursuant to a registration statement on Form S-3 filed on August 14, 2014. The Company received net proceeds of approximately $30.7 million, after deducting underwriting discounts and commissions and estimated offering-related transaction costs. Immediately following the offering, the Company used $11.2 million of the net proceeds to repurchase and retire 2,166,836 shares of its common stock from funds affiliated with Advent Private Equity (collectively Advent) at a price of $5.17 per share, which is equal to the net proceeds per share that the Company received from the offering, before expenses, pursuant to a stock purchase agreement the Company entered into with Advent in May 2017.

Warrants

In 2013, the Company issued warrants exercisable for 1,124,026 shares of Series B preferred stock, at an exercise price of $0.90 per share, to certain existing investors in conjunction with a private placement (the 2013 Warrants) and warrants exercisable for 111,112 shares of Series B preferred stock, at an exercise price of $0.90 per share, to Oxford Finance LLC and Silicon Valley Bank in conjunction with the Company’s entry into a loan and security agreement (the Lender Warrants). Upon completion of the IPO, the 2013 Warrants and the Lender Warrants became exercisable for 136,236 and 13,468 shares of common stock, respectively, at an exercise price of $7.43 per share. The 2013 Warrants and the Lender Warrants will expire on May 30, 2018 and July 3, 2023, respectively.

Stock Options

The following table summarizes the Company’s stock option activity under all stock option plans for the six months ended June 30, 2017:

	Total Options			Weighted- Average Exercise Price
Balance at December 31, 2016		3,393,813		$	5.10
Granted		1,059,100			4.43
Exercised		(51,757	)		1.15
Cancelled		(72,412	)		4.42
Balance at June 30, 2017		4,328,744		$	5.00

Stock-Based Compensation

The Company recorded stock-based compensation of $0.8 million and $0.8 million for the three months ended June 30, 2017 and 2016, respectively, and $2.1 million and $1.7 million for the six months ended June 30, 2017 and 2016, respectively.

Common Stock Reserved for Future Issuance

The following shares of common stock were reserved for future issuance at June 30, 2017:

Warrants to purchase common stock			149,704
Common stock options issued and outstanding			4,328,744
Common stock authorized for future option grants			613,503
Common stock authorized for the ESPP			544,578
Shares issuable upon conversion of convertible note payable			2,465,647
Total			8,102,176