8. PREFERRED STOCK WARRANTS AND COMMON STOCK WARRANTS

Immediately prior to the IPO, warrants outstanding consisted of the following:



Issuance Date	Underlying Security	Exercise Price	Number of Shares Issuable Upon Exercise	Warrant Contractual Term	Classification
July 1, 2012	Common stock	$ 0.002	485,985(1)	(1)	Liability
August 22, 2013	Series D preferred stock	$ 2.9891	167,500	10 years	Liability
June 27, 2014	Series D preferred stock	$ 2.9891	167,500	9.2 years	Liability
July 31, 2014	Common stock	$ 3.02	106,250	10 years	Equity

(1)The number of shares of common stock issuable upon the exercise of the Company’s liability‑classified warrant to purchase common stock is calculated based on the number of shares of common stock equal to 12.5% of the sum of (a) the number of shares of common stock into which the outstanding shares of Series A preferred stock, including shares issuable upon the exercise of outstanding options to purchase shares of Series A preferred stock, convert upon an IPO and (b) the number of shares of common stock underlying the warrant. Such warrant is only exercisable upon the closing of an IPO of shares of the Company’s common stock. The warrant will expire, if not exercised, on the day immediately following the closing of an IPO of shares of the Company’s common stock.

Upon closing of the IPO, the common stock warrant with an issuance date of July 1, 2012, became exercisable and was net exercised at an exercise price of $0.002 per share to purchase 485,985 shares of common stock.

Upon the closing of the IPO, the warrants to purchase the Series D preferred stock became warrants to purchase common stock. Subsequent to the IPO and prior to June 30, 2018, these common stock warrants were net exercised at an exercise price of $2.9891 per share to purchase 130,965 shares of common stock.

Subsequent to the IPO and prior to June 30, 2018, the common stock warrant with an issuance date of July 31, 2014, was net exercised at an exercise price of $3.02 per share to purchase 95,113 shares of common stock.

As of June 30, 2018, there were no preferred stock warrants or common stock warrants outstanding.