On March 8, 2018, the Company filed the 2018 Shelf Registration Statement covering the potential offering, issuance, and sale of an indeterminate amount of common stock, preferred stock, debt securities, warrants and/or units. In May 2018, the Company completed a follow-on offering under the 2018 Shelf Registration Statement pursuant to which the Company issued 3,750,000 shares of common stock at a price of $49.00 per share. In June 2018, the Company sold an additional 211,147 shares of common stock directly to the underwriters when they partially exercised their over-allotment option at the price of $49.00 per share. In the quarter ended June 30, 2018, the Company received proceeds totaling approximately $181.9 million from the offering, net of underwriting discounts and commissions and offering expenses, which includes approximately $9.7 million received due to the underwriters’ partial exercise of their over-allotment option.

The Company has reserved shares of common stock, on an as-if-converted basis, for issuance as follows:

	December 31, 2018		December 31, 2017
Options and awards issued and outstanding		3,864,407		2,964,549
Shares available for issuance under 2015 Stock Option and Incentive Plan		904,785		863,538
Shares available for issuance under 2015 Employee Stock Purchase Plan		780,716		449,444
Total		5,549,908		4,277,531

As amended in November 2015, the Company's Certificate of Incorporation authorizes 5,000,000 shares of preferred stock at a par value of $0.0001 per share. As of December 31, 2018 and 2017, no preferred stock was issued or outstanding.