Stock Option Plan

6 Months Ended

Jun. 30, 2026

Stock Option Plan [Abstract]

Stock Option Plan

12. Stock Option Plan

Equity Incentive Plan

In 2010, the Company adopted the 2010 Equity Compensation Plan (the “2010 Plan”). There have been no issuances under the 2010 Plan since the adoption of the 2016 Equity Incentive Plan (the “2016 Plan”). The 2010 Plan expired in 2025, and all options available for issuance under the 2010 Plan upon expiration were moved to the 2016 Plan. Accordingly, no shares are available for future issuance under the 2010 Plan as of June 30, 2026.

In 2016, the Company’s Board of Directors adopted the 2016 Plan under which incentive stock options (“ISOs”), nonqualified stock options (“NSOs”), stock appreciation rights (“SARs”), restricted stock, and restricted stock units (“RSUs”) may be granted to employees, directors, and consultants.

In connection with the Merger, the Company adopted the 2026 Equity Incentive Plan (the “2026 EIP”) effective on April 9, 2026. Pursuant to the Merger Agreement, the 2010 Plan and the 2016 Plan were terminated effective as of the closing of the Merger, and no further awards may be granted thereunder. All outstanding Legacy Ionetix stock options were assumed by the Company under the 2026 EIP and converted into options to purchase shares of the Company’s common stock, with the number of underlying shares and exercise price adjusted based on the Conversion Ratio. The converted options otherwise continued to be subject to substantially the same terms and conditions applicable to such options immediately prior to the Merger. The 2026 EIP provides for the issuance of incentive awards of ISOs, NSOs, SARs, RSUs and Stock Bonus Awards (“SBAs”). ISOs may be granted only to employees. The maximum aggregate number of shares of common stock that may be issued under the 2026 EIP is 11,935,631 shares.

Stock option

Stock option activity during the six months ended June 30, 2026 was as follows:

		Number of options				Weighted average exercise price				Weighted average remaining contractual life (years)				Aggregate intrinsic value
Balance as of December 31, 2025			14,162,648			$	0.31				6.41			$	2,541
Retroactive application of reverse recapitalization			(7,061,496	)
Balance as of December 31, 2025			7,101,152				0.62				6.41				2,541
Options granted			357,965				2.17
Options exercised			(447,117	)			0.30								1,107
Options cancelled			(423,460	)			0.55
Balance as of June 30, 2026			6,588,540			$	0.73				6.45			$	14,952
Vested and expected to vest at June 30, 2026			6,588,540			$	0.73				6.45			$	14,952
Exercisable at June 30, 2026			4,563,093			$	0.56				5.40			$	11,136

The options granted during the three months ended June 30, 2026 and 2025 had a weighted-average grant-date fair value per share of $2.08 and $0.61, respectively, and the options granted during the six months ended June 30, 2026 and 2025 had a weighted-average grant-date fair value per share of $1.97 and $0.60, respectively. The total fair value of options vested was $100 and $97 during the three months ended June 30, 2026 and 2025, respectively, and $308 and $272 during the six months ended June 30, 2026 and 2025, respectively.

Fair Value Inputs

The fair value of stock options granted was estimated using the following weighted-average assumptions:

		Six Months Ended June 30,
		2026				2025
Expected term (in years)			6.1				6.1
Expected volatility			65.6	%			64.9	%
Risk-free rate			4.1	%			4.1	%
Dividend yield			—				—

Stock-Based Compensation

The Company’s total stock-based compensation for the three and six months ended June 30, 2026 and 2025 was as follows:

		Three Months Ended June 30,								Six Months Ended June 30,
		2026				2025				2026				2025
Cost of revenue		$	16			$	3			$	34			$	6
Research and development			13				14				24				25
Selling, general and administrative			122				89				218				258
Total stock-based compensation		$	151			$	106			$	276			$	289

As of June 30, 2026 the unrecognized stock-based compensation related to outstanding unvested options was $1.5 million and is expected to be recognized over a weighted average period of 2.6 years.