11. Stock-Based Compensation

Stock Options

A summary of stock option activity during the periods indicated is as follows:

 

 

 

Number of Stock Option Awards

 

 

Weighted Average Exercise Price

 

 

Weighted
Average
Remaining Contractual Term (in years)

 

 

Aggregate Intrinsic Value (in thousands)

 

Balance at December 31, 2023

 

 

6,639,811

 

 

$

6.37

 

 

 

8.48

 

 

$

13,377

 

Granted

 

 

4,204,325

 

 

$

3.72

 

 

 

9.25

 

 

$

 

Exercised

 

 

(18,757

)

 

$

2.72

 

 

 

 

 

 

 

Canceled

 

 

(599,946

)

 

$

5.10

 

 

 

 

 

 

 

Balance at December 31, 2024

 

 

10,225,433

 

 

$

5.52

 

 

 

8.18

 

 

$

 

Exercisable at December 31, 2024

 

 

5,162,703

 

 

$

7.52

 

 

 

7.58

 

 

$

 

Nonvested at December 31, 2024

 

 

5,062,730

 

 

$

3.46

 

 

 

8.79

 

 

$

 

 

The Company uses the Black-Scholes option pricing model to estimate the fair value of each stock option award on the date of grant. The assumptions and estimates are as follows:

Expected term - The expected term represents the period of time that stock option awards are expected to remain outstanding. The Company estimates the expected term as the midpoint between actual or expected vesting date and the contractual term.
Expected volatility - The expected volatility was derived from the historical stock volatilities of peer public companies within the Company's industry that are considered to be comparable businesses over a period equivalent to the expected term of the stock option awards, since there has been limited trading history of the Company's stock.
Risk-free interest rate - The risk-free interest rate is based on the U.S. Treasury yield curve in effect at the date of grant for zero-coupon U.S. Treasury notes with maturities approximately equal to the stock option awards’ expected term.
Expected dividend yield - The expected dividend yield is zero as the Company has no plans to make dividend payments.

The following table sets forth the weighted average assumptions used in estimating the fair value of stock option awards on the grant date:

 

 

 

Year Ended December 31,

 

 

2024

 

 

 

2023

 

 

Expected volatility

 

 

87.6

 

%

 

84.0 - 85.8

 

%

Risk-free interest rate

 

 

4.30

 

%

 

3.73 - 3.93

 

%

Expected term (in years)

 

 

6.0

 

 

 

5.1 - 5.9

 

 

Expected dividend yield

 

 

 

%

 

 

 

%

As of December 31, 2024, there was $18.4 million of unrecognized stock-based compensation expense related to stock options which is expected to be recognized over a weighted-average period of approximately 2.6 years.

Restricted Stock Units

A summary of RSU activity during the periods indicated is as follows:

 

 

 

Number of Restricted Stock Units

 

 

Weighted Average Grant-Date Fair Value per Share

 

Balance at December 31, 2023

 

 

1,276,111

 

 

$

7.16

 

Vested

 

 

(394,760

)

 

$

7.29

 

Forfeited

 

 

(69,458

)

 

$

7.42

 

Balance at December 31, 2024

 

 

811,893

 

 

$

7.08

 

As of December 31, 2024, there was $4.9 million of unrecognized stock-based compensation expense related to RSUs which is expected to be recognized over a weighted-average period of approximately 2.0 years. The total fair value of RSUs vested was $1.1 million for the year ended December 31, 2024.

Restricted Stock Awards

A summary of RSA activity during the periods indicated is as follows:

 

 

 

Number of Restricted Stock Awards

 

 

Weighted Average Grant-Date Fair Value per Share

 

Balance at December 31, 2023

 

 

33,586

 

 

$

6.15

 

Vested

 

 

(30,002

)

 

$

6.14

 

Forfeited

 

 

(327

)

 

$

6.13

 

Balance at December 31, 2024

 

 

3,257

 

 

$

6.17

 

As of December 31, 2024, unrecognized stock-based compensation expense related to RSAs was de minimis which is expected to be recognized over a weighted-average period of approximately 0.1 years. The total fair value of RSAs vested was $0.1 million for the year ended December 31, 2024.

ESPP

As of December 31, 2024, 0.2 million shares of Class A common stock have been issued under the ESPP. During the years ended December 31, 2024 and 2023, the Company recognized $0.2 million and $0.3 million, respectively, of stock-based compensation expense related to the ESPP. As of December 31, 2024, unrecognized stock-based compensation expense related to the ESPP was de minimis which is expected to be recognized over a weighted-average period of approximately 0.1 years. As of December 31, 2024, contributions withheld from employees was de minimis and are recorded as a component of accrued expenses and other current liabilities in the consolidated balance sheet.

Stock-Based Compensation Expense

The following table summarizes the components of stock-based compensation expense resulting from the grant of stock options, RSUs, RSAs, and the ESPP, recorded in the Company’s consolidated statement of operations and comprehensive loss (in thousands):

 

 

 

Year Ended December 31,

 

 

 

2024

 

 

2023

 

Research and development

 

$

4,700

 

 

$

6,407

 

General and administrative

 

 

11,331

 

 

 

12,601

 

Total stock-based compensation

 

$

16,031

 

 

$

19,008

 

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.