12. Stock-based Compensation

On July 15, 2021, in connection with the completion of the Company’s IPO, the Company adopted a new comprehensive equity incentive plan, the 2021 Omnibus Equity Incentive Plan (the “2021 Plan”). Following the effective date of the 2021 Plan, no further awards may be issued under the 2018 Plan or the 2019 Plan (collectively, the “Prior Plans”). However, all awards under the Prior Plans that are outstanding as of the effective date of the 2021 Plan will continue to be governed by the terms, conditions and procedures set forth in the Prior Plans and any applicable award agreements. A total of 1,302,326 shares of common stock were reserved for issuance pursuant to the 2021 Plan prior to our annual meeting on June 26, 2023. Shareholders approved an increase to the number of shares reserved on June 26, 2023, and accordingly, at December 31, 2023, approximately 12,775,996 shares are reserved for issuance. The 2021 Plan provides for the issuance of incentive stock options, non-statutory stock options, stock appreciation rights, restricted stock, restricted stock units, and other stock-based awards. As of December 31, 2022, approximately 389,676 shares of common stock were available under the 2021 Plan. As of December 31, 2023, there are approximately 2,815,503 shares of common stock available under the 2021 Plan.

The following table summarizes activity for stock options under all plans for the year ended December 31, 2023:

The grant date fair value of options granted during the year ended December 31, 2023 was $5.7 million.

As of December 31, 2023, the unrecognized compensation cost related to outstanding stock options was $5 million, which is expected to be recognized as expense over approximately 2.9 years.

During August 2023, the Company granted a consultant 10,000 restricted stock units with a grant date fair value of $7,500, resulting in a fair value per share of $0.75. Subject to the consultant’s continued service, the restricted stock units shall vest upon the two-year anniversary of the date of grant. As of December 31, 2023, the unrecognized compensation cost related to the grant was approximately $4,000, which is expected to be recognized as expense over approximately 15 months.

During the year ended December 31, 2021, employees and consultants exercised a total of 383,721 stock options and the Company received $119,000 in proceeds. A portion of these options were exercised early (prior to vesting), and as of December 31, 2023, 1,357 of the options remained unvested. Proceeds received related to the unvested options of approximately $4,000 at December 31, 2023 were included in accrued liabilities on the accompanying balance sheet and will be reclassified to equity as vesting occurs, provided the employees and consultants continue to provide services to the Company. Proceeds received related to the vested portion of options of $27,000 were reclassified to equity during the year ended December 31, 2023. The vested portion of the exercises was 382,364 shares at December 31, 2023.

During May 2022, the Company granted a consultant 10,000 restricted stock units with a grant date fair value of $7,200, resulting in a fair value per share of $0.72. Subject to the consultant’s continued service, the restricted stock units shall vest upon the two-year anniversary of the date of grant. As of December 31, 2023, the unrecognized compensation cost related to the grant was approximately $1,000, which is expected to be recognized as expense over approximately 5 months.

During July 2021, the Company granted a director 26,738 restricted stock units with a grant date fair value of $100,000, resulting in a fair value per share of $3.74. The restricted stock units vested in July 2022.

The Company has recorded stock-based compensation expense, which includes expense related to restricted stock units, allocated by functional cost as follows for the years ended December 31, 2022 and 2023 (in thousands):

Fair Value of Stock Options

The assumptions are based on the following for each of the periods presented:

Expected Term - The expected term is calculated using the simplified method which is used when there is insufficient historical data about exercise patterns and post-vesting employment termination behavior. The simplified method is based on the vesting period and the contractual term for each grant, or for each vesting-tranche for awards with graded vesting. The mid-point between the vesting date and the maximum contractual expiration date is used as the expected term under this method.

Common Stock Fair Value - The fair value of the common stock underlying the Company’s stock options prior to the initial public offering was estimated at each grant date and was determined on a periodic basis and based either on transactions with third parties in which common stock was sold for cash or with the assistance of an independent third-party valuation expert. Subsequent to our initial public offering, the fair value underlying the Company’s common stock is determined based on the public market closing price on each date of grant. The assumptions underlying these valuations represented management’s best estimates, which involved inherent uncertainties and the application of significant levels of management judgment.

Volatility - The expected volatility being used is derived from the historical stock volatilities of a representative industry peer group of comparable publicly listed companies over a period approximately equal to the expected term of the options.

Risk-free Interest Rate - The risk-free interest rate is based on median U.S. Treasury zero coupon issues with remaining terms similar to the expected term on the options.

Expected Dividend – Through December 31, 2023, the Company has never declared nor paid any cash dividends. The Company shall modify its dividend policy to state that the Company intends to pay dividends to all stockholders, including holders of Series A Preferred Stock on an as-if-converted-to-common-stock basis, on a quarterly basis in an amount of which the aggregate of all quarterly dividends shall equal at least seventy-five percent (75%) of its annual net cash flow from operations following the approval of Oxylanthanum Carbonate by the FDA if obtained, and the commencement of commercial sales.

The following averaged assumptions were used to calculate the fair value of awards granted to employees, directors and non-employees for the years ended December 31, 2022 and 2023: