Kodiak Sciences Inc. Notes to Consolidated Financial Statements (in thousands, except share and per share data) 104 Restri t cted t Shares Restricted share activity, including restricted stock awards, restricted stock units, and performance-based restricted stock units, under the 2018 Plan is summarized as follows: Number of Restricted Shares Weighted Average Grant Date Fair Value Unvested at December 31, 2022 280,522 $ 60.17 Granted 30,250 $ 5.72 Vested (116,403) $ 61.98 Canceled (29,552) $ 54.77 Unvested at December 31, 2023 164,817 $ 49.87 Empl m oy l ee Restri t cted t Stoc t k Unitst The Company granted 28,750 RSUs to employees in 2023. The total fair value of RSUs vested during the year ended December 31, 2023, 2022, and 2021 was $4.8 million, $4.9 million and $3.2 million, respectively. Stock-based compensation expense recognized during the years ended December 31, 2023, 2022 and 2021 for RSUs was $4.5 million, $4.6 million, and $4.4 million, respectively. Non-Em - pl m oy l ee Awards The Company granted 22,500 stock options and 1,500 RSUs to non-employees during the year ended December 31, 2023. The fair value of non-employee stock options was estimated using the following weighted-average assumptions: Year Ended December 31, Year Ended December 31, Year Ended December 31, 2023 2022 2021 Expected volatility 88% — 60% Risk-free interest rate 3.82% — 0.97% Dividend yield 0% — 0% Expected term 4.11 — 5.69 The Company granted no stock options or RSUs to non-employees during the year ended December 31, 2022. Stock- based compensation expense recognized during the years ended December 31, 2023, 2022 and 2021 for equity awards granted to non-employees was $0.9 million, $1.2 million and $1.2 million, respectively. Perfor f ma r nce-Ba - sed Awards d In December 2019, the Company granted 170,150 performance-based stock options and 128,900 performance-based RSUs (collectively "2019 PSA"). These equity awards would vest 25% upon the achievement of specific f clinical development milestones. The remaining awards would then vest in three equal annual installments afte f r that date. The performance criteria for 2019 PSA was achieved in June 2021. 37,925 of the performance-based stock options and 25,907 of the performance-based restricted stock vested during 2023. The total fair value of the performance-based stock options and RSUs vested during the years ended December 31, 2023, 2022 and 2021 was $3.7 million, $3.9 million and $4.2 million, respectively. The Company estimated the fair value of the 2019 PSA using the Black-Scholes valuation model and significant assumptions included an expected volatility of 72%, a risk-fre f e rate of 1.67%, expected dividend yield of 0%, and expected term of 6.31 years. In Februa r ry 2021, the Company granted 190,831 performance-based stock options ("2021 Feb PSO"). These stock options will vest 25% upon the achievement of specific clinical development milestones. The remaining awards would then vest in 36 successive equal monthly installments afte f r the performance criteria is achieved. The performance criteria for 2021 Feb PSOs was achieved in Februa r ry 2022. 40,509 of the performance-based stock options vested during 2023. The total fair value of the performance-based stock options vested during the year ended December 31, 2023 and 2022 was $3.1 million and $6.2 million, respectively.