Kodiak Sciences Inc. Notes to Consolidated Financial Statements (in thousands, except share and per share data) 126 Stock-based compensation expense recognized during the years ended December 31, 2018, 2017 and 2016 for options granted to non-employees was $0.4 million, less than $0.1 million and less than $0.1 million, respectively. Restricted Stock Awards Restricted stock award (“RSAs”) activity is summarized as follows: Number of Shares Underlying Outstanding RSAs Weighted Average Grant Date Fair Value Unvested, December 31, 2016 ..................................................................................... 549,351 $ 0.41 Vested........................................................................................................................... (257,718) $ 1.00 Unvested, December 31, 2017 ..................................................................................... 291,633 $ 0.45 Granted......................................................................................................................... 27,500 $ 5.38 Vested........................................................................................................................... (268,683) $ 0.89 Unvested, December 31, 2018 ..................................................................................... 50,450 $ 0.79 Under the terms of the restricted stock agreements, 1/48th of the award vests monthly over four years, which is the requisite service period. Recipients of restricted stock awards generally have voting and dividend rights with respect to such shares upon grant without regard to vesting. Shares of restricted stock that do not vest are subject to forfeiture. The Company recognizes stock-based compensation expense for RSAs on a straight-line basis over the requisite service period for the entire award. The total value of RSAs vested during the years ended December 31, 2018, 2017 and 2016 was $0.2 million, $0.1 million and $0.1 million, respectively. During the years ended December 31, 2018, 2017 and 2016, stock-based compensation expense recognized for RSAs was $0.2 million, $0.1 million and $0.1 million, respectively. The Company granted 60,000 RSUs under the 2018 Plan and recognized stock-based compensation expense of less than $0.1 million for the year ended December 31, 2018. 2018 Employee Share Purchase Plan In August 2018, the Company adopted the 2018 Employee Share Purchase Plan (“ESPP”), which became effective on the business day prior to the effectiveness of the registration statement relating to the IPO. A total of 460,000 shares of common stock were initially reserved for issuance under the ESPP. The offering period and purchase period will be determined by the board of directors. As of December 31, 2018, no offerings have been authorized to date. Stock-Based Compensation Expense Stock-based compensation is classified in the consolidated statements of operations and comprehensive loss as follows (in thousands): Year Ended December 31, 2018 Year Ended December 31, 2017 Year Ended December 31, 2016 Research and development........................................................................ $ 1,535 $ 171 $ 88 General and administrative ....................................................................... 1,073 104 184 Total stock-based compensation ............................................................... $ 2,608 $ 275 $ 272 As of December 31, 2018, the unrecognized stock-based compensation of unvested employee options and unvested RSAs and RSUs was $15.7 million and expected to be recognized over a weighted-average period of 1.69 years. As of December 31, 2017, the unrecognized stock-based compensation of unvested employee options and unvested RSAs was $0.5 million and expected to be recognized over a weighted-average period of 0.95 years.