BIIB

SEC source: 0001127602-22-017808 · form4.xml · nonDerivative · entry 1

Rowinsky Eric K · CIK 0001318886 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 19,214

SEC source: 0001127602-22-017797 · form4.xml · nonDerivative · entry 1

Mulligan Richard · CIK 0001376247 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 15,099

SEC source: 0001127602-22-017796 · form4.xml · nonDerivative · entry 1

Mantas Jesus B · CIK 0001777331 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 5,088

SEC source: 0001127602-22-017793 · form4.xml · nonDerivative · entry 1

JONES WILLIAM D /CA/ · CIK 0001228380 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 2,145

SEC source: 0001127602-22-017781 · form4.xml · nonDerivative · entry 1

HAWKINS WILLIAM A · CIK 0001106508 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 4,190

SEC source: 0001127602-22-017779 · form4.xml · nonDerivative · entry 1

Freire Maria C · CIK 0001547999 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 2,145

SEC source: 0001127602-22-017773 · form4.xml · nonDerivative · entry 1

DENNER ALEXANDER J · CIK 0001361754 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 15,099

SEC source: 0001127602-22-017776 · form4.xml · nonDerivative · entry 1

DORSA CAROLINE · CIK 0001181174 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 23,242

SEC source: 0001127602-23-002504 · form5.xml · nonDerivative · entry 1

Posner Brian S · CIK 0001372455 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 8,025

SEC source: 0001127602-22-011610 · form4.xml · derivative · entry 3

Murphy Nicole · CIK 0001910644 · Head of Pharm Ops and Tech

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 479

Underlying: Common Stock · 239 shares

Expires 2024-04-01

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · price: Each restricted stock unit is converted to one share of common stock upon vesting.

F2 · derivative.exercise_date: This award was granted to the reporting person on April 1, 2021 and vested with respect to 239 shares on April 1, 2022. The remaining portion of the award vests in equal installments on each of the second and third anniversary of the grant date.

SEC source: 0001127602-22-011610 · form4.xml · nonDerivative · entry 2

Murphy Nicole · CIK 0001910644 · Head of Pharm Ops and Tech

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 1,812.89

SEC source: 0001127602-22-011610 · form4.xml · nonDerivative · entry 1

Murphy Nicole · CIK 0001910644 · Head of Pharm Ops and Tech

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 1,896.89

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · price: Each restricted stock unit is converted to one share of common stock upon vesting.

SEC source: 0001127602-22-006280 · form4.xml · derivative · entry 4

Vounatsos Michel · CIK 0001672709 · Director · Chief Executive Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 30,210

Underlying: Common Stock · 8,909 shares

Expires 2024-02-18

F2 · kind: This represents the difference between the maximum possible number of shares that were eligible for vesting and the actual number that vested.

F1 · derivative.exercise_date: The number of RSUs reported represents the maximum possible number of shares that are eligible for vesting, which is 200% of the number of shares at target payout. One-third of these RSUs are eligible to vest on each of the first three anniversaries of the grant date. The actual number of shares that will vest on each vesting date will be determined by comparing the price of Biogen common stock on such vesting date to the price on the grant date (i.e., number of vested shares = number of shares at target payout times [the 30-day average closing stock price ending on the vesting date divided by the 30-day average closing stock price on the grant date]).

SEC source: 0001127602-22-006280 · form4.xml · derivative · entry 3

Vounatsos Michel · CIK 0001672709 · Director · Chief Executive Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 39,119

Underlying: Common Stock · 6,191 shares

Expires 2024-02-18

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · derivative.exercise_date: The number of RSUs reported represents the maximum possible number of shares that are eligible for vesting, which is 200% of the number of shares at target payout. One-third of these RSUs are eligible to vest on each of the first three anniversaries of the grant date. The actual number of shares that will vest on each vesting date will be determined by comparing the price of Biogen common stock on such vesting date to the price on the grant date (i.e., number of vested shares = number of shares at target payout times [the 30-day average closing stock price ending on the vesting date divided by the 30-day average closing stock price on the grant date]).

SEC source: 0001127602-22-006280 · form4.xml · nonDerivative · entry 2

Vounatsos Michel · CIK 0001672709 · Director · Chief Executive Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 67,261.188

SEC source: 0001127602-22-006280 · form4.xml · nonDerivative · entry 1

Vounatsos Michel · CIK 0001672709 · Director · Chief Executive Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 70,007.188

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

SEC source: 0001127602-22-006271 · form4.xml · derivative · entry 4

Kramer Robin · CIK 0001609222 · Chief Accounting Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 1,934

Underlying: Common Stock · 570 shares

Expires 2024-02-18

F2 · kind: This represents the difference between the maximum possible number of shares that were eligible for vesting and the actual number that vested.

F1 · derivative.exercise_date: The number of RSUs reported represents the maximum possible number of shares that are eligible for vesting, which is 200% of the number of shares at target payout. One-third of these RSUs are eligible to vest on each of the first three anniversaries of the grant date. The actual number of shares that will vest on each vesting date will be determined by comparing the price of Biogen common stock on such vesting date to the price on the grant date (i.e., number of vested shares = number of shares at target payout times [the 30-day average closing stock price ending on the vesting date divided by the 30-day average closing stock price on the grant date]).

SEC source: 0001127602-22-006271 · form4.xml · derivative · entry 3

Kramer Robin · CIK 0001609222 · Chief Accounting Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 2,504

Underlying: Common Stock · 396 shares

Expires 2024-02-18

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · derivative.exercise_date: The number of RSUs reported represents the maximum possible number of shares that are eligible for vesting, which is 200% of the number of shares at target payout. One-third of these RSUs are eligible to vest on each of the first three anniversaries of the grant date. The actual number of shares that will vest on each vesting date will be determined by comparing the price of Biogen common stock on such vesting date to the price on the grant date (i.e., number of vested shares = number of shares at target payout times [the 30-day average closing stock price ending on the vesting date divided by the 30-day average closing stock price on the grant date]).

SEC source: 0001127602-22-006271 · form4.xml · nonDerivative · entry 2

Kramer Robin · CIK 0001609222 · Chief Accounting Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 1,737.348

SEC source: 0001127602-22-006271 · form4.xml · nonDerivative · entry 1

Kramer Robin · CIK 0001609222 · Chief Accounting Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 1,854.348

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

SEC source: 0001127602-22-006275 · form4.xml · derivative · entry 4

MCDONNELL MICHAEL R · CIK 0001121897 · EVP, Chief Financial Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 9,668

Underlying: Common Stock · 2,851 shares

Expires 2024-02-18

F2 · kind: This represents the difference between the maximum possible number of shares that were eligible for vesting and the actual number that vested.

F1 · derivative.exercise_date: The number of RSUs reported represents the maximum possible number of shares that are eligible for vesting, which is 200% of the number of shares at target payout. One-third of these RSUs are eligible to vest on each of the first three anniversaries of the grant date. The actual number of shares that will vest on each vesting date will be determined by comparing the price of Biogen common stock on such vesting date to the price on the grant date (i.e., number of vested shares = number of shares at target payout times [the 30-day average closing stock price ending on the vesting date divided by the 30-day average closing stock price on the grant date]).

SEC source: 0001127602-22-006275 · form4.xml · derivative · entry 3

MCDONNELL MICHAEL R · CIK 0001121897 · EVP, Chief Financial Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 12,519

Underlying: Common Stock · 1,981 shares

Expires 2024-02-18

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · derivative.exercise_date: The number of RSUs reported represents the maximum possible number of shares that are eligible for vesting, which is 200% of the number of shares at target payout. One-third of these RSUs are eligible to vest on each of the first three anniversaries of the grant date. The actual number of shares that will vest on each vesting date will be determined by comparing the price of Biogen common stock on such vesting date to the price on the grant date (i.e., number of vested shares = number of shares at target payout times [the 30-day average closing stock price ending on the vesting date divided by the 30-day average closing stock price on the grant date]).

SEC source: 0001127602-22-006275 · form4.xml · nonDerivative · entry 2

MCDONNELL MICHAEL R · CIK 0001121897 · EVP, Chief Financial Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 4,427

SEC source: 0001127602-22-006275 · form4.xml · nonDerivative · entry 1

MCDONNELL MICHAEL R · CIK 0001121897 · EVP, Chief Financial Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 5,404

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

SEC source: 0001127602-22-006269 · form4.xml · derivative · entry 4

Izzar Rachid · CIK 0001875506 · Head of Alzheimer's Disease

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 2,902

Underlying: Common Stock · 854 shares

Expires 2024-02-18

F2 · kind: This represents the difference between the maximum possible number of shares that were eligible for vesting and the actual number that vested.

F1 · derivative.exercise_date: This award was granted to the reporting person on February 18, 2021. The number of RSUs reported represents the maximum possible number of shares that are eligible for vesting, which is 200% of the number of shares at target payout. One-third of these RSUs are eligible to vest on each of the first three anniversaries of the grant date. The actual number of shares that will vest on each vesting date will be determined by comparing the price of Biogen common stock on such vesting date to the price on the grant date (i.e., number of vested shares = number of shares at target payout times [the 30-day average closing stock price ending on the vesting date divided by the 30-day average closing stock price following and including the grant date]).

SEC source: 0001127602-22-006269 · form4.xml · derivative · entry 3

Izzar Rachid · CIK 0001875506 · Head of Alzheimer's Disease

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 3,756

Underlying: Common Stock · 594 shares

Expires 2024-02-18

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · derivative.exercise_date: This award was granted to the reporting person on February 18, 2021. The number of RSUs reported represents the maximum possible number of shares that are eligible for vesting, which is 200% of the number of shares at target payout. One-third of these RSUs are eligible to vest on each of the first three anniversaries of the grant date. The actual number of shares that will vest on each vesting date will be determined by comparing the price of Biogen common stock on such vesting date to the price on the grant date (i.e., number of vested shares = number of shares at target payout times [the 30-day average closing stock price ending on the vesting date divided by the 30-day average closing stock price following and including the grant date]).

SEC source: 0001127602-22-006269 · form4.xml · nonDerivative · entry 2

Izzar Rachid · CIK 0001875506 · Head of Alzheimer's Disease

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 1,754

SEC source: 0001127602-22-006269 · form4.xml · nonDerivative · entry 1

Izzar Rachid · CIK 0001875506 · Head of Alzheimer's Disease

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 1,929

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

SEC source: 0001127602-22-006278 · form4.xml · derivative · entry 4

Murphy Nicole · CIK 0001910644 · Head of Pharm Ops and Tech

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 1,814

Underlying: Common Stock · 535 shares

Expires 2024-02-18

F2 · kind: This represents the difference between the maximum possible number of shares that were eligible for vesting and the actual number that vested.

F1 · derivative.exercise_date: This award was granted to the reporting person on February 18, 2021. The number of RSUs reported represents the maximum possible number of shares that are eligible for vesting, which is 200% of the number of shares at target payout. One-third of these RSUs are eligible to vest on each of the first three anniversaries of the grant date. The actual number of shares that will vest on each vesting date will be determined by comparing the price of Biogen common stock on such vesting date to the price on the grant date (i.e., number of vested shares = number of shares at target payout times [the 30-day average closing stock price ending on the vesting date divided by the 30-day average closing stock price following and including the grant date]).

SEC source: 0001127602-22-006278 · form4.xml · derivative · entry 3

Murphy Nicole · CIK 0001910644 · Head of Pharm Ops and Tech

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 2,349

Underlying: Common Stock · 371 shares

Expires 2024-02-18

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · derivative.exercise_date: This award was granted to the reporting person on February 18, 2021. The number of RSUs reported represents the maximum possible number of shares that are eligible for vesting, which is 200% of the number of shares at target payout. One-third of these RSUs are eligible to vest on each of the first three anniversaries of the grant date. The actual number of shares that will vest on each vesting date will be determined by comparing the price of Biogen common stock on such vesting date to the price on the grant date (i.e., number of vested shares = number of shares at target payout times [the 30-day average closing stock price ending on the vesting date divided by the 30-day average closing stock price following and including the grant date]).

SEC source: 0001127602-22-006278 · form4.xml · nonDerivative · entry 2

Murphy Nicole · CIK 0001910644 · Head of Pharm Ops and Tech

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 1,657.89

SEC source: 0001127602-22-006278 · form4.xml · nonDerivative · entry 1

Murphy Nicole · CIK 0001910644 · Head of Pharm Ops and Tech

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 1,767.89

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

SEC source: 0001127602-22-006266 · form4.xml · derivative · entry 4

Guindo Chirfi · CIK 0001722753 · Head of Glob Prod Strat & Com

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 9,668

Underlying: Common Stock · 2,851 shares

Expires 2024-02-18

F2 · kind: This represents the difference between the maximum possible number of shares that were eligible for vesting and the actual number that vested.

F1 · derivative.exercise_date: The number of RSUs reported represents the maximum possible number of shares that are eligible for vesting, which is 200% of the number of shares at target payout. One-third of these RSUs are eligible to vest on each of the first three anniversaries of the grant date. The actual number of shares that will vest on each vesting date will be determined by comparing the price of Biogen common stock on such vesting date to the price on the grant date (i.e., number of vested shares = number of shares at target payout times [the 30-day average closing stock price ending on the vesting date divided by the 30-day average closing stock price on the grant date]).

SEC source: 0001127602-22-006266 · form4.xml · derivative · entry 3

Guindo Chirfi · CIK 0001722753 · Head of Glob Prod Strat & Com

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 12,519

Underlying: Common Stock · 1,981 shares

Expires 2024-02-18

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · derivative.exercise_date: The number of RSUs reported represents the maximum possible number of shares that are eligible for vesting, which is 200% of the number of shares at target payout. One-third of these RSUs are eligible to vest on each of the first three anniversaries of the grant date. The actual number of shares that will vest on each vesting date will be determined by comparing the price of Biogen common stock on such vesting date to the price on the grant date (i.e., number of vested shares = number of shares at target payout times [the 30-day average closing stock price ending on the vesting date divided by the 30-day average closing stock price on the grant date]).

SEC source: 0001127602-22-006266 · form4.xml · nonDerivative · entry 2

Guindo Chirfi · CIK 0001722753 · Head of Glob Prod Strat & Com

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 7,364

SEC source: 0001127602-22-006266 · form4.xml · nonDerivative · entry 1

Guindo Chirfi · CIK 0001722753 · Head of Glob Prod Strat & Com

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 8,243

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

SEC source: 0001127602-22-006264 · form4.xml · derivative · entry 4

Gregory Ginger · CIK 0001545716 · EVP, Human Resources

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 6,768

Underlying: Common Stock · 1,995 shares

Expires 2024-02-18

F2 · kind: This represents the difference between the maximum possible number of shares that were eligible for vesting and the actual number that vested.

F1 · derivative.exercise_date: The number of RSUs reported represents the maximum possible number of shares that are eligible for vesting, which is 200% of the number of shares at target payout. One-third of these RSUs are eligible to vest on each of the first three anniversaries of the grant date. The actual number of shares that will vest on each vesting date will be determined by comparing the price of Biogen common stock on such vesting date to the price on the grant date (i.e., number of vested shares = number of shares at target payout times [the 30-day average closing stock price ending on the vesting date divided by the 30-day average closing stock price on the grant date]).

SEC source: 0001127602-22-006264 · form4.xml · derivative · entry 3

Gregory Ginger · CIK 0001545716 · EVP, Human Resources

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 8,763

Underlying: Common Stock · 1,387 shares

Expires 2024-02-18

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · derivative.exercise_date: The number of RSUs reported represents the maximum possible number of shares that are eligible for vesting, which is 200% of the number of shares at target payout. One-third of these RSUs are eligible to vest on each of the first three anniversaries of the grant date. The actual number of shares that will vest on each vesting date will be determined by comparing the price of Biogen common stock on such vesting date to the price on the grant date (i.e., number of vested shares = number of shares at target payout times [the 30-day average closing stock price ending on the vesting date divided by the 30-day average closing stock price on the grant date]).

SEC source: 0001127602-22-006264 · form4.xml · nonDerivative · entry 2

Gregory Ginger · CIK 0001545716 · EVP, Human Resources

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 11,218.6165

SEC source: 0001127602-22-006264 · form4.xml · nonDerivative · entry 1

Gregory Ginger · CIK 0001545716 · EVP, Human Resources

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 11,834.6165

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

SEC source: 0001127602-22-006262 · form4.xml · derivative · entry 4

ALEXANDER SUSAN H · CIK 0001263839 · EVP Chief Legal Off & Corp Sec

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 7,248

Underlying: Common Stock · 2,137 shares

Expires 2024-02-18

F2 · kind: This represents the difference between the maximum possible number of shares that were eligible for vesting and the actual number that vested.

F1 · derivative.exercise_date: The number of RSUs reported represents the maximum possible number of shares that are eligible for vesting, which is 200% of the number of shares at target payout. One-third of these RSUs are eligible to vest on each of the first three anniversaries of the grant date. The actual number of shares that will vest on each vesting date will be determined by comparing the price of Biogen common stock on such vesting date to the price on the grant date (i.e., number of vested shares = number of shares at target payout times [the 30-day average closing stock price ending on the vesting date divided by the 30-day average closing stock price on the grant date]).

SEC source: 0001127602-22-006262 · form4.xml · derivative · entry 3

ALEXANDER SUSAN H · CIK 0001263839 · EVP Chief Legal Off & Corp Sec

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 9,385

Underlying: Common Stock · 1,485 shares

Expires 2024-02-18

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · derivative.exercise_date: The number of RSUs reported represents the maximum possible number of shares that are eligible for vesting, which is 200% of the number of shares at target payout. One-third of these RSUs are eligible to vest on each of the first three anniversaries of the grant date. The actual number of shares that will vest on each vesting date will be determined by comparing the price of Biogen common stock on such vesting date to the price on the grant date (i.e., number of vested shares = number of shares at target payout times [the 30-day average closing stock price ending on the vesting date divided by the 30-day average closing stock price on the grant date]).

SEC source: 0001127602-22-006262 · form4.xml · nonDerivative · entry 2

ALEXANDER SUSAN H · CIK 0001263839 · EVP Chief Legal Off & Corp Sec

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 44,928

SEC source: 0001127602-22-006262 · form4.xml · nonDerivative · entry 1

ALEXANDER SUSAN H · CIK 0001263839 · EVP Chief Legal Off & Corp Sec

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 45,587

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

SEC source: 0001127602-22-004993 · form4.xml · derivative · entry 9

ALEXANDER SUSAN H · CIK 0001263839 · EVP Chief Legal Off & Corp Sec

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 3,218

Underlying: Common Stock · 2,090 shares

Expires 2023-02-12

F3 · kind: This represents the difference between the maximum possible number of shares that were eligible for vesting and the actual number that vested.

F2 · derivative.exercise_date: The number of RSUs reported represents the maximum possible number of shares that are eligible for vesting, which is 200% of the number of shares at target payout. One-third of these RSUs are eligible to vest on each of the first three anniversaries of the grant date. The actual number of shares that will vest on each vesting date will be determined by comparing the price of Biogen common stock on such vesting date to the price on the grant date (i.e., number of vested shares = number of shares at target payout times [the 30-day average closing stock price ending on the vesting date divided by the 30-day average closing stock price following and including the grant date]).

SEC source: 0001127602-22-004993 · form4.xml · derivative · entry 8

ALEXANDER SUSAN H · CIK 0001263839 · EVP Chief Legal Off & Corp Sec

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 5,308

Underlying: Common Stock · 1,126 shares

Expires 2023-02-12

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F2 · derivative.exercise_date: The number of RSUs reported represents the maximum possible number of shares that are eligible for vesting, which is 200% of the number of shares at target payout. One-third of these RSUs are eligible to vest on each of the first three anniversaries of the grant date. The actual number of shares that will vest on each vesting date will be determined by comparing the price of Biogen common stock on such vesting date to the price on the grant date (i.e., number of vested shares = number of shares at target payout times [the 30-day average closing stock price ending on the vesting date divided by the 30-day average closing stock price following and including the grant date]).

SEC source: 0001127602-22-004993 · form4.xml · derivative · entry 7

ALEXANDER SUSAN H · CIK 0001263839 · EVP Chief Legal Off & Corp Sec

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 2,190 shares

Expires 2022-02-12

F3 · kind: This represents the difference between the maximum possible number of shares that were eligible for vesting and the actual number that vested.

F2 · derivative.exercise_date: The number of RSUs reported represents the maximum possible number of shares that are eligible for vesting, which is 200% of the number of shares at target payout. One-third of these RSUs are eligible to vest on each of the first three anniversaries of the grant date. The actual number of shares that will vest on each vesting date will be determined by comparing the price of Biogen common stock on such vesting date to the price on the grant date (i.e., number of vested shares = number of shares at target payout times [the 30-day average closing stock price ending on the vesting date divided by the 30-day average closing stock price following and including the grant date]).

SEC source: 0001127602-22-004993 · form4.xml · derivative · entry 6

ALEXANDER SUSAN H · CIK 0001263839 · EVP Chief Legal Off & Corp Sec

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 2,190

Underlying: Common Stock · 1,154 shares

Expires 2022-02-12

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F2 · derivative.exercise_date: The number of RSUs reported represents the maximum possible number of shares that are eligible for vesting, which is 200% of the number of shares at target payout. One-third of these RSUs are eligible to vest on each of the first three anniversaries of the grant date. The actual number of shares that will vest on each vesting date will be determined by comparing the price of Biogen common stock on such vesting date to the price on the grant date (i.e., number of vested shares = number of shares at target payout times [the 30-day average closing stock price ending on the vesting date divided by the 30-day average closing stock price following and including the grant date]).

SEC source: 0001127602-22-004993 · form4.xml · nonDerivative · entry 5

ALEXANDER SUSAN H · CIK 0001263839 · EVP Chief Legal Off & Corp Sec

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 44,102

F1 · kind: Represents shares withheld to satisfy the withholding tax liability due upon vesting of shares, as previously disclosed by reporting person on January 21, 2022.

SEC source: 0001127602-22-004993 · form4.xml · nonDerivative · entry 4

ALEXANDER SUSAN H · CIK 0001263839 · EVP Chief Legal Off & Corp Sec

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 45,146