Biogen Phase 2 CELIA trial data sent shares down 6.4% after it was revealed that topline data missed its primary endpoint.

NEW YORK , May 18, 2026 /PRNewswire/ -- Biogen Inc. (NASDAQ: BIIB) shareholders lost 6.4% per share on May 14, 2026, when Phase 2 "CELIA" topline data for diranersen missed its primary dose-response endpoint. Investors who held BIIB through the drop are encouraged to submit their information to discuss their legal rights. You may also contact Joseph E. Levi, Esq. via email at jlevi@SueWallSt.com or by telephone at (888) SueWallSt.

On May 14, Biogen released CELIA topline data showing the trial failed to meet its primary endpoint. In particular, CELIA did not meet its primary endpoint assessing dose response for change from baseline on the Clinical Dementia Rating–Sum of Boxes (CDR-SB) at Week 76. Despite this, the Company plans to advance diranersen to registrational development.

Shareholders who suffered losses on their BIIB investment may click here to get more information about this investigation. You may also contact Joseph E. Levi, Esq. via email at jlevi@SueWallSt.com or by telephone at (888) SueWallSt.

SueWallSt | Top 50 Securities Firm | (888) SueWallSt | www.suewallst.com

Frequently Asked Questions About the BIIB Investigation

Q: How much did BIIB stock drop?A: Shares fell approximately 5-6% on May 14, 2026, after Biogen disclosed that its Phase 2 CELIA trial for diranersen failed to meet its primary dose-response endpoint. Investors who purchased shares before the drop may be eligible to participate in the investigation.

Q: What do BIIB investors need to do right now?A: Gather brokerage records including purchase dates, share quantities, and prices paid. Contact SueWallSt for a free, no-obligation evaluation at jlevi@SueWallSt.com or (888) SueWallSt. No immediate action is required to remain eligible to participate in the investigation.

Q: What if I already sold my BIIB shares -- can I still recover losses?A: Yes. Eligibility is based on when you purchased, not whether you still hold the shares. Investors who bought BIIB and sold at a loss may still participate in the investigation.

Q: What does it cost me to participate?A: Nothing. Securities investigations and any resulting actions are handled on a pure contingency basis. No upfront fees, no retainer, no out-of-pocket costs.

Q: What if I live outside the United States?A: U.S. securities fraud investigations generally cover purchases on U.S. exchanges regardless of the investor's country of residence.

CONTACT:
SueWallSt
Joseph E. Levi, Esq.
Ed Korsinsky, Esq.
33 Whitehall Street, 27th Floor
New York, NY 10004
jlevi@SueWallSt.com
Tel: (888) SueWallSt
Fax: (212) 363-7171

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SOURCE SueWallSt.com