5.   STOCKHOLDERS' EQUITY (DEFICIT), STOCK OPTION PLANS, AND STOCK-BASED COMPENSATION

Our authorized capital stock consists of:

As of June 30, 2025 there were 68,003,613 shares of our common stock outstanding, and no shares of preferred stock outstanding. As of December 31, 2024, there were 46,579,199 shares of our common stock outstanding, and no shares of preferred stock outstanding.

As of June 30, 2025, the Company has shares of common stock reserved for future issuance as follows:

May 2025 ATM Sales Agreement

On May 30, 2025, the Company entered into an at market issuance sales agreement (the “May 2025 ATM Sales Agreement”) with B. Riley Securities, Inc. and Alliance Global Partners serving as agents (the “Agents”), with respect to an at-the-market ("ATM") offering program under which the Company may offer and sell, from time to time at its sole discretion, shares of its common stock having an aggregate offering price of up to $50 million through the Agents. During the three and six months ended June 30, 2025, the Company sold 1,263,664 shares of common stock pursuant to the May 2025 ATM Sales Agreement for net proceeds of $0.7 million after deducting sales agent commissions and other offering expenses of approximately $0.3 million.

2020 Equity Incentive Plan

Subsequent to the December 31, 2024 balance sheet date, in accordance with the “evergreen” provision in our 2020 Equity Incentive Plan (the "Evergreen Provision"), an additional 4,657,919 shares (the “Evergreen Shares”) were automatically made available for issuance on the first day of 2025, which represents 10% of the number of shares of common stock outstanding on December 31, 2024. The Evergreen Shares are included in the 2020 Equity Incentive Plan share reserve as of June 30, 2025 as presented in the table above.

Stock-based Compensation Expense

The Company records stock-based compensation expense based on the fair value of stock options granted to employees, non-employee consultants and non-employee directors. During the three months ended June 30, 2025 and 2024, the Company recorded stock-based compensation expense of approximately $0.4 million in each period. During the six months ended June 30, 2025 and 2024, the Company recorded stock-based compensation expense of approximately $1.3 million and $0.7 million, respectively. As of June 30, 2025, the Company had unrecognized stock-based compensation expense of $1.9 million, which is expected to be recognized over a weighted-average period of 1.7 years.

Determining Fair Value

Valuation and Recognition – The fair value of each option award is estimated on the date of grant using the Black-Scholes option-pricing model. The Black-Scholes pricing model utilizes assumptions regarding volatility of the Company's common share price, expected term, expected divided rate, and risk-free interest rates as described below:

The fair value of options granted during the six months ended June 30, 2025 used the following weighted average assumptions and key inputs:

The fair value of options granted during the three months ended June 30, 2025 used the following weighted average assumptions and key inputs:

The weighted average fair value of stock options granted for the three and six months ended June 30, 2025 was $0.68 and $1.46, respectively. The options have a contractual term of 10 years. No options were granted during the three and six months ended June 30, 2024.

Activity under the Company's equity compensation plan for the six months ended June 30, 2025 is as follows:

For the three months ended June 30, 2025 and 2024, the amount of stock-based compensation expense included within research and development and general and administrative expenses was as follows:

For the six months ended June 30, 2025 and 2024, the amount of stock-based compensation expense included within research and development and general and administrative expenses was as follows: