Stock-based compensation is included under the following expense categories presented in the condensed consolidated statements of operations (in thousands):


	Three Months Ended March 31,
	2026		2025
Research and development	$	1,938	$	440
General and administrative		1,933		187
Total	$	3,871	$	627

In January 2017, the Company adopted the 2016 Equity Incentive Plan (“2016 Plan”). The 2016 Plan provides for the grant of stock-based incentive awards, including common stock options and other forms of stock-based compensation. Any cancelled or forfeited awards under the 2016 Plan become available for future issuances. As of March 31, 2026, no shares were reserved for future issuance under the 2016 Plan.

In August 2025, the Company adopted the 2025 Stock Option and Incentive Plan (“2025 Plan”). The 2025 Plan provides for the grant of equity and equity-based incentive awards, such as stock options and other forms of stock-based compensation, to officers, employees, directors, and consultants. Any cancelled or forfeited awards under the 2025 Plan become available for future issuances. As of March 31, 2026, 1,521,834 shares were available for future grants under the 2025 Plan.

In August 2025, the Company adopted the 2025 Employee Stock Purchase Plan (“ESPP”). Under the ESPP, eligible employees may purchase shares of BBOT’s common stock through payroll deductions at a price equal to 85% of the fair market value of the common stock on the offering date or the exercise date, whichever is less. As of March 31, 2026, 1,808,313 shares were available for future grants under the ESPP, and no offering periods had started.

In October 2025, the Company adopted the 2025 Inducement Plan (“2025 Inducement Plan”) to be used for grants of equity-based awards to individuals who were not previously its employees or directors as an inducement for entry into employment. Any cancelled or forfeited awards under the 2025 Inducement Plan become available for future issuances. As of March 31, 2026, 852,500 shares were available for future grants under the 2025 Inducement Plan.

The Company had the following common stock options outstanding:


	Number of Options			Weighted-Average Exercise Price		Weighted-Average Remaining Contractual Term (Years)		Aggregate Intrinsic Value (In thousands)
Outstanding as of December 31, 2025		9,035,498		$	7.79		9.0	$	42,771
Granted		3,228,045			11.19
Exercised		(97,163	)		4.28
Forfeited and cancelled		(102,251	)		8.68
Outstanding as of March 31, 2026		12,064,129		$	8.72		9.2	$	15,908
Exercisable as of March 31, 2026		2,226,329		$	6.26		8.6	$	6,936

The aggregate intrinsic value in the above table is calculated as the difference between the estimated fair value of the Company’s common stock and the exercise price of the underlying stock options as of each reporting date.

As of March 31, 2026, a total of 1,730,153 common stock options included provisions for accelerated vesting in connection with a qualified change in control of the Company. These instruments included 1,507,214 options, with vesting if the grantee is terminated without cause, as defined in the 2016 Plan, or for good reason, as defined in the grant terms, within 12 months following such a transaction. The remaining 222,939 options vest immediately upon the occurrence of a qualified change in control, excluding events such as an initial public offering or other bona fide financing transactions. The closing of the de-SPAC Transaction described in Note 1 did not constitute a qualified change in control event under these definitions.

The weighted-average grant-date fair value of common stock options granted during three months ended March 31, 2026 was $7.52 per share. The weighted-average grant-date fair value of common stock options vested and forfeited during the three months ended March 31, 2026 was, $4.10 and $6.57 per share, respectively. As of March 31, 2026, there was $61.5 million of unrecognized stock-based compensation related to unvested common stock options, which is expected to be recognized over a weighted-average period of 3.2 years.

There were no grants issued during the three months ended March 31, 2025. The fair value of stock options granted during the three months ended March 31, 2026 were estimated at the grant date using the Black-Scholes option pricing model based on the following assumptions:


		Three Months Ended March 31, 2026
Expected term, years		5.77 - 6.08
Expected volatility		71.18% - 74.03%
Expected dividends		—
Risk-free interest rate		3.8% - 4.1%

Activity under the 2025 Plan with respect to the Company’s RSUs during the three months ended March 31, 2026 was as follows:


	Number of Shares		Weighted-Average Grant Date Fair Value
Outstanding as of December 31, 2025		—	$	—
Granted		368,470		—
Vested and released		—		—
Forfeited and cancelled		—		—
Unvested and expected to vest at March 31, 2026		368,470	$	10.19

As of March 31, 2026, there was $3.7 million of total unrecognized compensation cost related to RSUs that is expected to be recognized over a weighted average period of 3.8 years.

10. Stock-Based Compensation