12. Subsequent Events

2018 Stock Option and Incentive Plan

On April 17, 2018, the Company's board of directors adopted, and on April 19, 2018, the Company's stockholders approved, the 2018 Stock Option and Incentive Plan (the “2018 Plan”), which became effective on May 2, 2018, the date immediately preceding the effectiveness of the registration statement for the Company's IPO. The 2018 Plan provides for the grant of incentive stock options, nonqualified stock options, stock appreciation rights, restricted stock units, restricted stock awards, unrestricted stock awards and dividend equivalent rights. The number of shares initially reserved for issuance under the 2018 Plan is 6,075,051, plus the shares of common stock remaining available for issuance under the  Company's 2012 Stock Option and Grant Plan (the “2012 Plan”), which will be automatically increased on January 1, 2019 and each January 1 thereafter by 5% of the number of shares of the Company's common stock outstanding on the immediately preceding December 31 or a lesser number of shares determined by the Company's board of directors or the compensation committee of the board of directors. The shares of common stock underlying any awards that are forfeited, canceled, held back upon exercise or settlement of an award to satisfy the exercise price or tax withholding, reacquired by the Company prior to vesting, satisfied without any issuance of stock, expire or are otherwise terminated by the Company under the 2018 Plan, the 2012 Plan and the Company’s Amended and Restated Equity Incentive Plan will be added back to the shares of common stock available for issuance under the 2018 Plan.

2018 Employee Stock Purchase Plan

On April 17, 2018, the Company's board of directors adopted, and on April 19, 2018, the Company's stockholders approved, the 2018 Employee Stock Purchase Plan (the “ESPP”), which became effective on May 2, 2018, the date immediately preceding the effectiveness of the registration statement for the Company's initial public offering. A total of 1,735,729 shares of common stock were reserved for issuance under this plan. In addition, the number of shares of common stock that may be issued under the ESPP will be cumulatively increased on January 1, 2019 and each January 1 thereafter through January 1, 2028, by the lesser of (i) 1% of the number of shares of the Company's common stock outstanding on the immediately preceding December 31, (ii) 1,735,729 shares of common stock or (iii) such lesser number of shares as determined by the compensation committee of the board of directors.

Grants of Stock Options and Restricted Stock Units

In May 2018, the Company granted options to purchase an aggregate of 885,820 and 216,950 shares of common stock, at an exercise price of $19.00 and $24.97 per share, respectively, to employees as compensation for future services to the Company. The options vest over a term of four years.

In May 2018, the Company granted restricted stock units that may be settled for an aggregate of 18,021 shares of common stock to directors as compensation for future services to the Company. The restricted stock units vest on the earlier of (i) one year from the date of grant or (ii) the next annual meeting of the Company stockholders, subject to the grantee maintaining a continuous service relationship with the Company.