9. Common Stock

The Company has authorized 300,000,000 shares of common stock, $0.001 par value, per share, of which 43,840,909 shares were issued and outstanding as of June 30, 2017 and 43,058,827 shares were issued and outstanding as of December 31, 2016.

During the three and six months ended June 30, 2017, the Company issued an aggregate of 89,462 shares of common stock upon exercise of stock options, including stock options to purchase 50,000 shares of common stock exercised through net exercise provisions resulting in the issuance of 19,462 shares of common stock and stock options to purchase 70,000 shares of common stock exercised for cash, providing cash proceeds of $0.2 million.

During the three and six months ended June 30, 2017, the Company issued an aggregate of 692,620 shares of common stock due to warrant exercises. Net exercise of 89,330 warrants resulted in the issuance of 49,127 shares of common stock. Additionally, 643,493 were exercised resulting in cash proceeds of $1.3 million.