9. Stock-based Compensation

Stock‑based compensation expense recognized was as follows (in thousands):

 

 

 

Year Ended December 31,

 

 

 

2024

 

 

2023

 

Research and development

 

$

4,043

 

 

$

4,003

 

General and administrative

 

 

7,006

 

 

 

6,620

 

Total stock-based compensation expense

 

$

11,049

 

 

$

10,623

 

 

Valuation Assumptions

The fair value of stock options was determined using the Black-Scholes option-pricing model and the assumptions below. Each of these inputs is subjective and generally required significant judgment.

Fair Value of Common Stock—The fair value of each share of common stock is based on the closing price of the Company’s common stock on the date of grant, or other relevant determination date, as reported on The Nasdaq Global Select Market.
Risk-Free Interest Rate—The risk-free interest rate is based on the U.S. Treasury zero coupon issues in effect at the time of grant for periods corresponding with the expected term of the option.
Expected Volatility—Because the Company was previously privately held and did not have any trading history for its common stock, the expected volatility was estimated based on the average volatility for comparable publicly traded life sciences companies over a period equal to the expected term of the stock option grants. The comparable companies were chosen based on the similar size, stage in life cycle or area of specialty. The Company will continue to apply this process until a sufficient amount of historical information regarding the volatility of its own stock price becomes available.
Expected Term—The expected term represents the period that the stock-based awards are expected to be outstanding and is determined using the simplified method (based on the midpoint between the vesting date and the end of the contractual term) as the Company has limited history of relevant stock option exercise activity.
Expected Dividend Yield—The Company has never paid dividends on its common stock and has no plans to pay dividends going forward. Therefore, it used an expected dividend yield of zero.

The fair value of each stock option was estimated using the Black‑Scholes option‑pricing model with the following weighted-average assumptions:

 

 

 

Year Ended December 31,

 

 

 

2024

 

 

2023

 

Risk-free interest rate

 

 

4.13

%

 

 

3.54

%

Expected volatility

 

 

97.21

%

 

 

99.18

%

Expected term (in years)

 

 

5.88

 

 

 

5.84

 

Expected dividend yield

 

 

 

 

 

 

 

The grant date fair value of restricted stock units is based upon the fair market value of the Company’s common stock based on its closing price as reported on the date of grant on the Nasdaq Global Select Market.

 

The fair value of options granted during the years ended December 31, 2024 and 2023 was $10.6 million and $9.8 million, respectively. The fair value of restricted stock units granted during the year ended December 31, 2024 and 2023 was $0.4 million and $0.5 million, respectively.

Stock Option Activity

Changes in shares available for grant under the 2020 Plan and the 2024 Inducement Plan during the year ended December 31, 2024 were as follows:

 

 

 

Shares
Available
for Grant

 

Shares available for grant at December 31, 2023

 

 

3,158,094

 

2020 Plan reserve increase on January 1, 2024

 

 

1,908,630

 

Shares reserved upon adoption of the
   2024 Inducement Plan

 

 

750,000

 

Options and restricted stock units granted

 

 

(5,986,613

)

Options and restricted stock units forfeited,
   cancelled, or expired

 

 

2,186,270

 

Shares available for grant at December 31, 2024

 

 

2,016,381

 

 

A summary of stock option activity under the 2020 Plan and the 2024 Inducement Plan for the year ended December 31, 2024 was as follows:

 

 

 

Shares

 

 

Weighted-
Average
Exercise
price
per Share

 

 

Weighted-
Average
Remaining
Contractual
Term
(in years)

 

 

Aggregate
Intrinsic
Value
(in
thousands)

 

Balance at December 31, 2023

 

 

6,820,869

 

 

$

7.97

 

 

8.24

 

 

$

387

 

Granted

 

 

5,052,871

 

 

 

2.64

 

 

 

 

 

 

 

Exercised

 

 

(75,660

)

 

 

0.16

 

 

 

 

 

 

 

Forfeited/expired

 

 

(2,185,770

)

 

 

4.21

 

 

 

 

 

 

 

Balance at December 31, 2024

 

 

9,612,310

 

 

$

6.08

 

 

 

8.08

 

 

$

130

 

Expected to vest

 

 

4,055,037

 

 

$

3.79

 

 

 

8.82

 

 

$

87

 

Options exercisable

 

 

5,557,273

 

 

$

7.75

 

 

 

7.53

 

 

$

43

 

 

 

The total fair value of options granted that vested during the years ended December 31, 2024 and 2023 was $11.0 million and $9.8 million, respectively.

The aggregate intrinsic value in the table above is calculated as the difference between the exercise price of the underlying options and the estimated fair value of the Company’s common stock underlying all options that were in-the-money at December 31, 2024. The aggregate intrinsic value of options exercised was $0.2 million and $0.2 million during the year ended December 31, 2024 and 2023, respectively, determined as of the date of option exercise. As of December 31, 2024, there was $9.8 million of total unrecognized compensation cost related to non-vested stock options. The Company expects to recognize this cost over a remaining weighted-average period of 1.99 years. The Company utilizes newly issued shares to satisfy option exercises.

Stock options outstanding and exercisable under the 2020 Plan and the 2024 Inducement Plan consisted of the following at December 31, 2024:

 

 

 

 

 

Exercise Price ($)

 

Options
Outstanding

 

 

Options
Exercisable

 

0.43 to 0.71

 

 

964,067

 

 

 

310,581

 

1.04 to 4.22

 

 

5,771,807

 

 

 

2,834,921

 

8.93 to 19.94

 

 

2,528,788

 

 

 

2,136,223

 

20.55 to 29.41

 

 

347,648

 

 

 

275,548

 

Total

 

 

9,612,310

 

 

 

5,557,273

 

 

Restricted Stock Unit Activity

A summary of restricted stock unit, or RSU, activity for the year ended December 31, 2024 is as follows:

 

 

 

Share
Equivalent

 

 

Weighted-
Average
Grant Date
Fair Value

 

Non-vested at December 31, 2023

 

 

310,087

 

 

$

11.44

 

Granted

 

 

933,742

 

 

 

0.46

 

Cancelled

 

 

(500

)

 

 

2.51

 

Vested

 

 

(620,668

)

 

 

5.94

 

Non-vested at December 31, 2024

 

 

622,661

 

 

$

0.46

 

As of December 31, 2024, there was $0.2 million of total unrecognized compensation cost related to non-vested RSUs. The Company expects to recognize this cost over a remaining weighted-average period of 0.77 years.

Employee Stock Purchase Plan

Under the ESPP, eligible employees can authorize payroll deductions for amounts up to the lesser of 15% of their qualifying wages or the statutory limit under the U.S. Internal Revenue Code. The ESPP provides for offering periods of six months in duration with one purchase period per offering period beginning May 18 and November 18 of each year. Participants in an offering period will be granted the right to purchase shares of our common stock at a price per share that is 85% of the lesser of the fair market value of the shares at (1) the first day of the offering period or (2) the end of each purchase period within the offering period. A maximum of 10,000 shares of common stock may be purchased by each participant at the purchase date during the offering period. The fair market value of the ESPP options granted is determined using the Black-Scholes model and is amortized on a straight-line basis. Stock-based

compensation expense recognized during the years ended December 31, 2024 and 2023 associated with the ESPP was $0.1 million and $0.1 million, respectively. During the year ended December 31, 2024, the Company issued 172,014 shares of common stock to employees under the ESPP.

Historical Timeline

Fiscal YearFiled
2024Feb 27, 2025Showing above
2021Mar 28, 2022

About Stock Compensation Disclosures

Stock-based compensation disclosures detail the equity awards granted to employees and executives — including stock options, restricted stock units (RSUs), and performance shares — along with the valuation methods and assumptions used to expense them. This section reveals the true cost of talent retention and the alignment between management incentives and shareholder interests.

Key signals: total unrecognized compensation expense and its expected recognition period signal future earnings headwinds from already-granted awards. For stock options, examine Black-Scholes assumptions — expected volatility, risk-free rate, and expected term — as understating any of these reduces reported compensation expense. Compare stock compensation expense as a percentage of revenue against peers to assess dilution cost. Watch vesting schedules for acceleration clauses tied to change-of-control events. Performance-based awards with undemanding targets may indicate weak governance. Add back stock compensation to operating cash flow to calculate a more conservative free cash flow figure.