
	For the Years Ended December 31,
(In millions)	2025		2024		2023
Research and development	$	115.7	$	154.1	$	296.7
Selling, general and administrative	187.8		198.6		371.7
Subtotal	303.5		352.7		668.4
Capitalized share-based compensation costs	(12.4)		(10.3)		(10.2)
Share-based compensation expense included in total cost and expense	291.1		342.4		658.2
Income tax effect	(57.0)		(63.4)		(132.6)
Share-based compensation expense included in net income attributable to Biogen Inc.	$	234.1	$	279.0	$	525.6

In connection with our acquisition of HI-Bio in July 2024 we recognized HI-Bio equity-based compensation expense, inclusive of employer taxes, of approximately $56.4 million attributable to the post-acquisition service period, of which $42.5 million was recognized as a charge to research and development expense with the remaining $13.9 million as a charge to selling, general and administrative expense within our consolidated statements of

income for the year ended December 31, 2024. These amounts were associated with the accelerated vesting of stock options and RSUs previously granted to HI-Bio employees and required no future services to vest.

In connection with our acquisition of Reata in September 2023 we recognized Reata equity-based compensation expense, inclusive of employer taxes, of approximately $393.4 million attributable to the post-acquisition service period, of which $196.4 million was recognized as a charge to selling, general and administrative expense with the remaining $197.0 million as a charge to research and development expense within our consolidated statements of income for the year ended December 31, 2023. These amounts were associated with the accelerated vesting of stock options and RSUs previously granted to Reata employees that required no future services to vest.


	For the Years Ended December 31,
(In millions)	2025		2024		2023
Time-vested restricted stock units	$	249.3	$	236.4	$	220.0
Performance stock units settled in stock	42.3		48.4		35.5
Performance stock units settled in cash	—		(2.5)		6.8
Employee stock purchase plan	8.4		9.7		10.5
Stock options	3.5		3.7		3.7
Market stock units	—		0.6		4.9
Reata equity awards(1)	—		—		387.0
HI-Bio equity awards(1)	—		56.4		—
Subtotal	303.5		352.7		668.4
Capitalized share-based compensation costs	(12.4)		(10.3)		(10.2)
Share-based compensation expense included in total cost and expense	$	291.1	$	342.4	$	658.2

(1) Relates to the Reata and HI-Bio equity-based compensation expense attributable to the post-acquisition service period, associated with the accelerated vesting of stock options and RSUs previously granted to Reata and HI-Bio employees that required no future services to vest. For additional information on our acquisitions of Reata and HI-Bio, please read Note 2, Acquisitions, to these consolidated financial statements.

As of December 31, 2025, unrecognized compensation cost related to unvested share-based compensation was approximately $292.6 million, net of estimated forfeitures. We expect to recognize the cost of these unvested awards over a weighted-average period of 1.9 years.

We have two share-based compensation plans pursuant to which awards are currently being made: (i) the Biogen Inc. 2024 Omnibus Equity Plan (2024 Omnibus Equity Plan); and (ii) the Biogen Inc. 2024 Employee Stock Purchase Plan (2024 ESPP).

We have three share-based compensation plans pursuant to which outstanding awards have been made, but from which no further awards can or will be made: (i) the Biogen Inc. 2006 Non-Employee Directors Equity Plan (2006 Directors Plan); (ii) the Biogen Inc. 2017 Omnibus Equity Plan (2017 Omnibus Equity Plan); and (iii) the Biogen Inc. 2015 Employee Stock Purchase Plan (2015 ESPP).

In June 2024 our shareholders approved the 2024 Omnibus Equity Plan for share-based awards to our prospective and current employees, non-employee directors, officers or consultants. Awards granted from the 2024 Omnibus Equity Plan may include stock options, shares of restricted stock, restricted stock units, performance shares, stock appreciation rights and other awards in such amounts and with such terms and conditions as may be determined by a committee of our Board of Directors, subject to the provisions of the plan. Shares of common stock available for grant under the 2024 Omnibus Equity Plan consist of 3.7 million shares reserved for this purpose, plus shares of common stock that remained available for grant under our 2017 Omnibus Equity Plan (including shares available by

reason of a predecessor plan) on the date that our shareholders approved the 2024 Omnibus Equity Plan, plus shares that were subject to awards under the 2017 Omnibus Equity Plan (including shares available by reason of a predecessor plan) that remain unissued upon the cancellation, surrender, exchange, termination or forfeiture of such awards. The 2024 Omnibus Equity Plan provides that awards other than stock options and stock appreciation rights will be counted against the total number of shares available under the plan in a 1.5-to-1 ratio.

We have not made any awards pursuant to the 2017 Omnibus Equity Plan or the Directors Plan since our shareholders approved the 2024 Omnibus Equity Plan, and do not intend to make any awards pursuant to the 2017 Omnibus Equity Plan or the Directors Plan in the future, except that unused shares under the 2017 Omnibus Equity Plan have been carried over for use under the 2024 Omnibus Equity Plan. Awards outstanding under the 2017 Omnibus Equity Plan and the Directors Plan as of the date our shareholders approved the 2024 Omnibus Equity Plan will remain outstanding and subject to the terms and conditions of the 2017 Omnibus Equity Plan and the Directors Plan, as applicable, and the relevant award agreements.

In 2022 we granted approximately 81,000 stock options to our CEO (2022 CEO Grant) under the 2017 Omnibus Plan with a grant date fair value of $139.10 per option for a total of approximately $11.2 million. The fair value of the stock option grant is estimated as of the date of grant using a Black-Scholes option valuation model. The estimated fair value of the stock option is then expensed over the options' vesting periods. The 2022 CEO Grant is eligible to vest in equal annual installments over a three-year period from the grant date, subject to the CEO’s continued employment. The outstanding stock option has a 10-year term and is exercisable at a price per share not less than the fair market value of the underlying common stock on the date of grant.


	December 31, 2025
	Shares	Weighted Average Exercise Price		Weighted Average Remaining Contractual Term
Outstanding at December 31, 2024	81,000	$	301.85	7.9 years
Granted	—	—
Exercised	—	—
Forfeited	—	—
Outstanding at December 31, 2025	81,000	$	301.85	6.9 years
Exercisable at December 31, 2025	81,000	$	301.85	6.9 years

MSUs awarded to employees in 2014 and thereafter vested in three equal annual increments beginning on the first anniversary of the grant date, and participants could ultimately earn between zero and 200.0% of the target number of units granted based on actual stock performance. The vesting of these awards was subject to the respective employee’s continued employment.

Beginning in 2022 we no longer grant MSUs as part of our long term incentive program and have replaced with granting performance-vested RSUs. The fair values of the remaining MSUs vested in 2024 and 2023 totaled $6.3 million and $20.7 million, respectively.

During the first quarter of 2018 we began granting awards for performance-vested RSUs that will settle in stock. PSUs awarded to employees have a three-year performance period and vest on the third anniversary of the grant date. The vesting of these awards is subject to the respective employee’s continued employment. The number of PSUs granted represents the target number of units that are eligible to be earned based on the achievement of cumulative three-year performance measures established at the beginning of the performance period, which ends on December 31 of the third year of the performance period.

Participants may ultimately earn between zero and 200.0% of the target number of PSUs granted based on the degree of achievement of the applicable performance metric. Accordingly, additional PSUs may be issued or currently outstanding PSUs may be cancelled upon final determination of the number of units earned.

Beginning in 2022 we no longer grant MSUs as part of our long term incentive program and have replaced with granting PSUs with a performance metric based on a three-year cumulative relative total shareholder return (rTSR) metric.

Beginning in 2024 we began granting PSUs with a performance metric based on the three-year cumulative aggregate growth rate of our earnings per share during the performance period.


	December 31, 2025
	Shares	Weighted Average Grant Date Fair Value
Unvested at December 31, 2024	550,000	$	310.61
Granted(1)	477,000	161.28
Vested	—	—
Forfeited	(222,000)	176.41
Unvested at December 31, 2025	805,000	$	227.39

(1) PSUs settled in stock granted in 2025 include awards granted in conjunction with our annual awards made in February 2025 and PSUs granted in conjunction with the hiring of employees. These grants reflect the target number of shares eligible to be earned at the time of grant.

We value grants of PSUs with a performance metric based on a three-year cumulative rTSR metric using a lattice model with a Monte Carlo simulation. This valuation methodology utilizes several key assumptions, the 30 calendar day average closing stock price on the date of grant for PSUs, expected volatility of our stock price, risk-free rates of return and expected dividend yield.


	For the Years Ended December 31,
	2025	2024	2023
Expected dividend yield	—%	—%	—%
Range of expected stock price volatility	34.5%	35.1%	44.7%
Range of risk-free interest rates	4.2%	4.1%	4.1%
30 calendar day average stock price on grant date	$146.46	$251.69	$283.93
Weighted-average per share grant date fair value	$196.13	$280.60	$383.61

During the first quarter of 2018 we began granting awards for performance-vested restricted stock units that would settle in cash. PSUs awarded to employees had three performance periods and vested on the third anniversary of the grant date. The vesting of these awards was subject to the respective employee’s continued employment. PSUs were classified as liability awards and were settled in cash based on the 30 calendar day average closing stock price through the vesting date, once the actual vested and earned number of PSUs was determined. Since no shares were issued, these awards did not dilute equity.

Beginning in 2022 we no longer grant PSUs settled in cash as part of our long term incentive program and have replaced with granting time-vested RSUs. The fair values of the remaining PSUs settled in cash that vested in 2024 and 2023 totaled $9.5 million and $11.7 million, respectively.

RSUs awarded to employees generally vest no sooner than one-third per year over three years on the anniversary of the date of grant, or upon the third anniversary of the date of the grant, provided the employee remains continuously employed with us, except as otherwise provided in the plan. Shares of our common stock will be delivered to the employee upon vesting, subject to payment of applicable withholding taxes. RSUs awarded to directors for service on

our Board of Directors vest on the first anniversary of the date of grant, provided in each case that the director continues to serve on our Board of Directors through the vesting date. Shares of our common stock will be delivered to the director upon vesting and are not subject to any withholding taxes.


	Shares	Weighted Average Grant Date Fair Value
Unvested at December 31, 2024	2,051,000	$	246.22
Granted(1)	2,385,000	141.71
Vested	(997,000)	243.92
Forfeited	(363,000)	188.28
Unvested at December 31, 2025	3,076,000	$	172.75

(1) RSUs granted in 2025 primarily represent RSUs granted in conjunction with our annual awards made in February 2025 and awards made in conjunction with the hiring of new employees. RSUs granted in 2025 also include approximately 24,500 RSUs granted to our Board of Directors.

In June 2024 our shareholders approved the 2024 ESPP. The 2024 ESPP, which became effective on July 1, 2024, replaced the 2015 ESPP, which expired on June 30, 2024. The maximum number of shares of our common stock that may be purchased under the 2024 ESPP is 2.5 million.


	For the Years Ended December 31,
(In millions, except share amounts)	2025		2024		2023
Shares issued under the 2024 ESPP	295,000		40,000		—
Shares issued under the 2015 ESPP	—		175,000		199,000
Cash received under the 2024 ESPP	$	34.0	$	5.1	$	—
Cash received under the 2015 ESPP	$	—	$	31.2	$	45.1