8. Stock-based compensation Stock-based compensation expense was included in general and administrative and research and development as follows (in thousands): | | | | | | | | | | | | | | | Three Months Ended | | Nine Months Ended | | | September 30, | | September 30, | | | 2024 | | 2023 | | 2024 | | 2023 | General and administrative | | $ | 103 | | $ | 172 | | $ | 273 | | $ | 111 | Research and development | | | 36 | | | — | | | 105 | | | 11 | Total stock-based compensation | | $ | 139 | | $ | 172 | | $ | 378 | | $ | 122 |
Stock-based award plans In June 2024, in connection with the 2024 Annual Meeting of Stockholders, our stockholders approved an amendment (the “Amendment”) to the NeuroBo Pharmaceuticals, Inc. 2022 Equity Incentive Plan (the “2022 Plan”). Pursuant to the terms and conditions of the Amendment, the 2022 Plan was amended to: | ● | automatically increase on January 1st of each year for a period of eight years commencing on January 1, 2025 and ending on (and including) January 1, 2032, the aggregate number of shares of common stock that may be issued pursuant to Awards (as defined in the 2022 Plan) to an amount equal to 10% of the Fully Diluted Shares (as defined in the 2022 Plan) as of the last day of the preceding calendar year, provided, however that the Board may act prior to the effective date of any such annual increase to provide that the increase for such year will be a lesser number of shares of common stock; and |
| ● | increase the aggregate maximum number of shares of common stock that may be issued pursuant to the exercise of Incentive Stock Options (as defined in the 2022 Plan) to 1 million shares of the common stock plus the amount of any increase in the number of shares that may be available for issuance pursuant to the annual increase described above, but in no event more than 15 million shares of the common stock issued as incentive stock options. |
The following table summarizes the outstanding awards issued pursuant to our stock-based award plans and inducement grants as of September 30, 2024 and the remaining shares of common stock available for future issuance: | | | | | | | | | | | | | Remaining shares of | | | Stock | | | | common stock available | Plan Name | | Options | | RSUs | | for future issuance | 2019 Equity Incentive Plan (the “2019 Plan”) | | 1,575 | | — | | — | 2022 Plan | | 3,125 | | 170,059 | | 393,222 | 2021 Inducement Plan | | — | | — | | 4,166 | Total | | 4,700 | | 170,059 | | 397,388 |
For stock options and RSUs granted under the 2019 Plan and 2022 Plan as of September 30, 2024, unrecognized stock-based compensation costs totaled $0.8 million. The unrecognized stock-based costs are expected to be recognized as an expense over a weighted average period of 1.7 years. Stock options The following table summarizes the status of our outstanding and exercisable options and related transactions for the period presented (in thousands, except share and per share amounts): | | | | | | | | | | | | | | | | | | | | | | | Outstanding | | Exercisable | | | Shares of | | | | | | | | Weighted | | Shares of | | | | | | | | Weighted | | | Common | | Weighted | | | | Average | | Common | | Weighted | | | | Average | | | Stock | | Average | | Aggregate | | Remaining | | Stock | | Average | | Aggregate | | Remaining | | | Issuable | | Exercise | | Intrinsic | | Contractual | | Issuable | | Exercise | | Intrinsic | | Contractual | | | for Options | | Price | | Value | | Term (years) | | for Options | | Price | | Value | | Term (years) | As of January 1, 2024 | | 4,700 | | $ | 398.30 | | $ | — | | 8.6 | | 4,577 | | $ | 391.04 | | $ | — | | 8.6 | Vested | | | | | | | | | | | | 104 | | | 747.38 | | | | | | As of September 30, 2024 | | 4,700 | | $ | 398.30 | | $ | — | | 7.8 | | 4,681 | | $ | 398.93 | | $ | — | | 7.8 |
Restricted Stock Units The following table summarizes the status of our RSUs and related transactions for the period presented (in thousands, except share and per share amounts): | | | | | | | | | | | | | | | | | | | Outstanding | | Vested and Deferred Release | | | Shares of | | Average | | | | Shares of | | Average | | | | | Common Stock | | Grant Date | | Aggregate | | Common Stock | | Grant Date | | Aggregate | | | Issuable | | Fair Value | | Intrinsic | | Issuable | | Fair Value | | Intrinsic | | | for RSUs | | Price | | Value | | for RSUs | | Price | | Value | As of January 1, 2024 | | 141,361 | | $ | 4.55 | | $ | 523 | | 5,469 | | $ | 4.02 | | $ | 20 | Granted | | 83,899 | | | 5.41 | | | | | | | | | | | | Vested and Deferred Release | | | | | | | | | | 14,768 | | | 4.29 | | | | Vested and Released | | (55,201) | | | 4.68 | | | 207 | | | | | | | | | As of September 30, 2024 | | 170,059 | | $ | 4.93 | | $ | 539 | | 20,237 | | $ | 4.21 | | $ | 64 |
Grant date fair value of stock options, warrants and restricted stock units We estimated the grant date fair value of stock options and warrants granted to employees, consultants (including placement agents for the offerings), and directors using the Black-Scholes option pricing model. The following assumptions used in the Black-Scholes option pricing model for stock options and warrants granted in 2024 and 2023 are as follows: | | | | | | | | | | | | | | | | | | Contingent | | Stock | | | Warrants Granted | | Warrants Granted | | Options Granted | | | in June 2024 | | in June 2024 | | in March 2023 | Weighted average fair value | | $ | 2.73 | | | $ | 3.43 | | | $ | 3.63 | | Expected stock price volatility | | | 140.0 | % | | | 127.0 | % | | | 82.9 | % | Expected term (years) | | | 2.1 | | | | 5.7 | | | | 5.0 | | Expected dividend yield | | | — | % | | | — | % | | | — | % | Risk-free interest rate | | | 463 | % | | | 4.31 | % | | | 3.54 | % |
We estimated the grant date fair value of restricted stock units granted to employees, consultants and directors based on the closing sales price of our common stock as reported on Nasdaq on the date of grant.
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