Portnoy Law Firm Announces Class Action on Behalf of Mereo BioPharma Group plc Investors

LOS ANGELES, March 16, 2026 (GLOBE NEWSWIRE) -- The Portnoy Law Firm advises Mereo BioPharma Group plc, (“Mereo” or the "Company") (NASDAQ: MREO) investors of a class action on behalf of investors that bought securities between June 5, 2023 and December 26, 2025, inclusive (the “Class Period”). Mereo investors have until April 6, 2026 to file a lead plaintiff motion.

Investors are encouraged to contact attorney Lesley F. Portnoy, by phone 844-767-8529 or email: [email protected], to discuss their legal rights, or join the case via https://portnoylaw.com/mereo-biopharma-group-plc. The Portnoy Law Firm can provide a complimentary case evaluation and discuss investors’ options for pursuing claims to recover their losses.

According to the complaint, defendants provided overwhelmingly positive statements to investors while, at the same time, disseminating materially false and misleading statements and/or concealing material adverse facts concerning the true state of the Phase 3 ORBIT and COSMIC programs; neither of which hit its primary endpoints of reducing annualized clinical fracture rate compared to the placebo or bisphosphonate control groups, respectively. On December 29, 2025, Mereo issued a press release announcing that neither the ORBIT nor the COSMIC Phase 3 studies achieved statistical significance. The press release indicated that neither study met its primary endpoint of reduction in annualized clinical fracture rate compared to placebo or bisphosphonates, respectively, despite improved bone mineral density. Following this news, the price of Mereo's ADS declined dramatically. From a closing market price of $2.31 per share on December 26, 2025, Mereo's ADS price fell to $0.29 per share on December 29, 2025, a decline of more than 87.7%.

The Portnoy Law Firm represents investors in pursuing claims caused by corporate wrongdoing. The Firm’s founding partner has recovered over $5.5 billion for aggrieved investors. Attorney advertising. Prior results do not guarantee similar outcomes.

Lesley F. Portnoy, Esq.
Admitted CA, NY and TX Bar
[email protected]
310-692-8883
www.portnoylaw.com

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