The following table presents the components of stock-based compensation expense:


(in millions)	Classification	Year ended December 31,
		2025		2024		2023
Stock options	Equity	$	9.3	$	10.5	$	13.7
RSUs	Equity	37.1		35.0		25.5


Other	Both	—		1.3		1.3
Total		$	46.4	$	46.8	$	40.5
Award classification:
Equity		$	47.6	$	47.0	$	40.2
Liability		(1.2)		(0.2)		0.3

We recognized a reduction to income tax expense as a result of tax benefits associated with our stock-based compensation plans of $3.0 million, $5.9 million and $5.0 million, in 2025, 2024 and 2023, respectively.

Our stock-based compensation awards have been issued under a succession of plans sponsored by the ultimate parent of our business, which is currently Avantor, Inc. In connection with our IPO, we adopted the 2019 Plan. The 2019 Plan provides for up to 23.5 million shares of common stock to be issued in the form of stock options, RSUs or other equity-based awards or cash-based awards. The 2019 Plan also provides for 1% annual increases to the number of shares of common stock available for issuance unless reduced by our Board of Directors. At December 31, 2025, 43.7 million shares were available for future issuance. The 2019 Plan will automatically terminate on May 17, 2029, and no award under the plan may be granted after this date.

The following table presents information about outstanding stock options:


(options and intrinsic value in millions)	Number of options	Weighted average exercise price per option		Aggregate intrinsic value		Weighted average remaining term
Balance on December 31, 2024	11.9	$	21.94
Granted	1.5	16.01
Exercised	(0.1)	7.80
Forfeited	(1.6)	22.57
Balance on December 31, 2025	11.7	$	21.18	$	—	4.2 years
Expected to vest	2.0	19.16		—		8.6 years
Vested	9.7	21.57		—		3.4 years

During 2025, we granted stock options with a contractual life of ten years that vest annually over two to three years, as specified in the underlying grant agreements, subject to the recipient continuously providing service to us through each applicable vesting period.

The following table presents weighted-average information about stock options granted:


	Year ended December 31,
	2025			2024			2023
Grant date fair value per option	$	6.05		$	9.86		$	9.64
Assumptions used to determine grant date fair value:
Expected stock price volatility	32		%	34		%	33		%
Risk free interest rate	4.2		%	4.3		%	4.1		%
Expected dividend rate	nil			nil			nil
Expected life of options	6.0 years			6.0 years			6.2 years

The following table presents other information about stock options:


(in millions)	Year ended December 31,
	2025		2024		2023
Fair value of options vested	$	12.5	$	13.7	$	14.2
Intrinsic value of options exercised	0.8		11.7		7.1

The following table presents information about unvested RSUs:


(awards in millions)	Number of awards	Weighted average grant date fair value per award
Balance on December 31, 2024	4.6	$	26.63
Granted	4.9	15.33
Vested	(1.3)	27.14
Forfeited	(1.5)	21.36
Balance on December 31, 2025	6.7	$	17.88

During 2025, we granted RSUs that vest annually over one to three years, as specified in the underlying grant agreements, subject to the recipient continuously providing service to us throughout the vesting period. Certain of those awards contain performance and market conditions that impact the number of shares that will ultimately vest. We recorded expense on such awards of $2.8 million, $9.3 million and $3.1 million, for the years ended December 31, 2025, 2024 and 2023, respectively.