Biogen Securities Litigation Settlement

Notice of Settlement:You are hereby notified that a hearing will be held on September 29, 2026, at 2:00 p.m., before the Honorable William G. Young, at the United States District Court, District of Massachusetts, John Joseph Moakley U.S. Courthouse, 1 Courthouse Way, Boston, MA 02210, Courtroom 18 – 5th Floor, to determine whether:

(1) the proposed settlement (the “Settlement”) of the above-captioned Action as set forth in the Stipulation and Agreement of Class Action Settlement, dated June 5, 2026 (“Stipulation”) for $18.9 million in cash should be approved by the Court as fair, reasonable, and adequate;

(2) the Judgment as provided under the Stipulation should be entered dismissing the Action with prejudice;

(3) to award Lead Counsel attorneys’ fees and expenses out of the Settlement Fund (as defined in the Notice of Proposed Settlement of Class Action (“Notice”), which is discussed below) and, if so, in what amounts;

(4) to award Lead Plaintiff expenses pursuant to 15 U.S.C. §78u-4(a)(4) in relation to their representation of the Class out of the Settlement Fund and, if so, in what amount; and

(5) the Plan of Allocation should be approved by the Court as fair, reasonable, and adequate.

It is possible that the Court may decide to change the date and/or time of the Settlement Hearing, conduct the Settlement Hearing by video or telephonic video conference, or otherwise allow Class Members to appear at the hearing by telephone or video conference, without further written notice to the Class. To determine whether the date and time of the Settlement Hearing have changed, or whether Class Members must or may participate by telephone or video, it is important that you monitor the Court’s docket and the website, www.BiogenSecuritiesLitigation.com, for any update before making any plans to attend the Settlement Hearing.

IF YOU PURCHASED OR ACQUIRED BIOGEN INC. (“BIOGEN”) COMMON STOCK BETWEEN JUNE 8, 2021 AND JULY 12, 2021, INCLUSIVE, YOUR RIGHTS MAY BE AFFECTED BY THE SETTLEMENT OF THIS LITIGATION

Proof of Claim: To share in the distribution of the Net Settlement Fund, you must establish your rights by submitting a Proof of Claim and Release form (“Proof of Claim”) by mail (postmarked no later than September 24, 2026) or electronically via the website (no later than 11:59 ET on September 24, 2026). Failure to submit your Proof of Claim by September 24, 2026 will subject your claim to rejection and preclude you from receiving any of the recovery in connection with the Settlement of this Action.

If you purchased or acquired Biogen common stock during the period between June 8, 2021 and July 12, 2021, inclusive, and do not request exclusion from the Class, you will be bound by the Settlement and any judgment and release entered in this Action, including, but not limited to, the Judgment, whether or not you submit a Proof of Claim.

Notice: The Notice, which more completely describes the Settlement and your rights thereunder (including your right to object to the Settlement), the Proof of Claim, the Stipulation (which, among other things, contains definitions for the defined terms used in this Summary Notice), and other important documents, may be accessed online at www.BiogenSecuritiesLitigation.com, or by writing to or calling:

Inquiries should NOT be directed to Defendants, the Court, or the Clerk of the Court. Inquiries other than requests for the Notice or for a Proof of Claim may be made to Lead Counsel:

Exclusion: If you desire to be excluded from the Class, you must submit a request for exclusion such that it is received by August 25, 2026, in the manner and form explained in the Notice. All Class members will be bound by the Settlement even if they do not submit a timely Proof of Claim.

Objections:If you are a Class member, you have the right to object to the Settlement, the Plan of Allocation, the request by Lead Counsel for an award of attorneys’ fees, and/or the request for an award to Lead Plaintiff in connection with its representation of the Class. Any objections must be filed with the Court and sent to Lead Counsel and Defendants’ counsel such that they are received by September 8, 2026, in the manner and form explained in the Notice available at www.BiogenSecuritiesLitigation.com.