Mereo BioPharma Shares Plunge 87.7% After Phase 3 Trial Failures
Written by Emily J. Thompson, Senior Investment Analyst
Updated: Feb 23 2026
0mins
Should l Buy MREO?
Source: Globenewswire
- Stock Crash: Mereo BioPharma's shares plummeted from $2.31 on December 26, 2025, to $0.29 on December 29, 2025, marking a staggering decline of over 87.7%, indicating a severe market reaction to the failure of both ORBIT and COSMIC Phase 3 trials to achieve statistical significance, leading to a collapse in investor confidence.
- Analyst Downgrades: Following the December 29 disclosure, analysts from Cantor, Baird, and J.P. Morgan swiftly downgraded Mereo's stock, with Needham reportedly lowering its price target by more than 28%, reflecting a pessimistic outlook on the company's future prospects in light of the trial failures.
- Early Warning Signs: As early as July 9, 2025, Mereo announced that the ORBIT study failed to achieve statistical significance during its second interim analysis, causing shares to drop from $2.94 to $1.69, a decline of approximately 42.52%, yet the company continued to issue misleading statements, failing to adequately warn investors.
- CEO Confidence Shift: Throughout the Class Period, CEO Denise Scots-Knight expressed confidence in setrusumab's success, but after the December 29 results, she stated her disappointment and commitment to further data analysis, highlighting a significant disconnect between public statements and the underlying reality faced by investors.
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Analyst Views on MREO
Wall Street analysts forecast MREO stock price to rise
8 Analyst Rating
6 Buy
2 Hold
0 Sell
Strong Buy
Current: 0.410
Low
0.50
Averages
2.08
High
5.00
Current: 0.410
Low
0.50
Averages
2.08
High
5.00
About MREO
Mereo BioPharma Group plc is a biopharmaceutical company focused on the development of therapeutics for rare diseases. The Company has developed a portfolio of late-stage clinical product candidates, and its two rare disease product candidates are setrusumab for the treatment of osteogenesis imperfecta (OI) and alvelestat primarily for the treatment of severe alpha-1 antitrypsin deficiency-associated lung disease (AATD-LD). In addition to the rare disease programs, it has two oncology product candidates in clinical development, which include Etigilimab, an IgG1 monoclonal antibody which binds to the human T-cell immunoreceptor with Ig and ITIM domains (TIGIT) receptor on immune cells to improve the activation and effectiveness of T-cell and NK cell antitumor activity and Navicixizumab is a bispecific antibody that inhibits delta-like ligand 4 (DLL4) and vascular endothelial growth factor (VEGF). Navicixizumab is developed for the treatment of late-line ovarian cancer.
About the author
Emily J. Thompson
Emily J. Thompson, a Chartered Financial Analyst (CFA) with 12 years in investment research, graduated with honors from the Wharton School. Specializing in industrial and technology stocks, she provides in-depth analysis for Intellectia’s earnings and market brief reports.
Class Action Reminder for Mereo BioPharma Shareholders
- Lawsuit Background: Robbins LLP reminds all investors who purchased Mereo BioPharma Group plc (NASDAQ: MREO) American Depository Shares between June 5, 2023, and December 26, 2025, that a class action has been filed, alleging the company misled investors regarding the results of its drug studies.
- Study Failures: The complaint highlights that Mereo's Phase 3 ORBIT and COSMIC studies for Osteogenesis Imperfecta failed to meet their primary endpoint of reducing annualized fracture rates, despite the company's prior confidence, leading investors to buy shares at artificially inflated prices.
- Stock Price Plunge: On December 29, 2025, Mereo announced that its studies did not meet expectations, causing the stock price to plummet from $2.31 per share on December 26, 2025, to $0.29 per share, a decline of over 87.7%, severely impacting shareholder value.
- Opportunity to Participate: Shareholders wishing to serve as lead plaintiffs in the class action must submit their papers by April 6, 2026, indicating the importance of corporate governance and shareholder rights in the wake of such significant losses.
See More
Mereo BioPharma Class Action Notice Issued
- Class Action Deadline: Rosen Law Firm reminds investors who purchased Mereo BioPharma ADS between June 5, 2023, and December 26, 2025, that they must apply to be lead plaintiff by April 6, 2026, or risk losing their right to compensation, emphasizing the urgency for affected investors to act promptly.
- Cost Arrangement: Investors participating in the class action will incur no out-of-pocket fees, as attorney fees will be covered through a contingency fee arrangement, significantly lowering the financial barrier for investors to seek compensation and encouraging broader participation in the lawsuit.
- Lawsuit Background: The lawsuit alleges that Mereo BioPharma made false statements regarding the efficacy of setrusumab in its Phase 3 Orbit and COSMIC studies, leading investors to purchase ADS at artificially inflated prices, which resulted in significant losses when the truth was revealed, highlighting serious issues in the company's disclosure practices.
- Law Firm Credentials: Rosen Law Firm is recognized for its success in securities class actions, having recovered over $438 million for investors in 2019 alone, and was ranked first in 2017 for the number of securities class action settlements, demonstrating its expertise and influence in handling such cases effectively.
See More
Class Action Filed Against Mereo BioPharma Group plc
- Lawsuit Background: Bronstein, Gewirtz & Grossman LLC has filed a class action lawsuit against Mereo BioPharma Group plc, alleging violations of federal securities laws on behalf of all investors who purchased Mereo securities between June 5, 2023, and December 26, 2025.
- False Statements Allegation: The complaint claims that throughout the class period, defendants made overwhelmingly positive statements while disseminating materially false and misleading information, concealing adverse facts about the Phase 3 ORBIT and COSMIC programs, both of which failed to meet their primary endpoints for reducing clinical fracture rates.
- Investor Action: Affected investors are encouraged to apply to be lead plaintiffs by April 6, 2026, to share in any potential recovery, with the assurance that participation does not require serving as lead plaintiff.
- Law Firm's Advantage: Bronstein, Gewirtz & Grossman LLC operates on a contingency fee basis, having successfully recovered hundreds of millions for investors nationwide, emphasizing their expertise in securities fraud class actions and the importance of maintaining market integrity.
See More
Faruqi & Faruqi Investigates Mereo BioPharma for Securities Violations
- Legal Investigation Launched: Faruq & Faruqi LLP is investigating potential securities claims against Mereo BioPharma, specifically urging investors who purchased securities between June 5, 2023, and December 26, 2025, to contact them before the April 6, 2026, deadline to seek lead plaintiff status.
- Lawsuit Allegations Overview: The lawsuit alleges that Mereo and its executives violated federal securities laws by failing to disclose the true status of the Phase 3 ORBIT and COSMIC programs, both of which failed to meet their primary endpoints for reducing clinical fracture rates, resulting in significant investor losses.
- Stock Price Plunge Impact: Following Mereo's announcement on December 29, 2025, that both Phase 3 studies failed to meet primary endpoints, the stock price plummeted by $2.02, or 87.64%, closing at $0.28 per share, reflecting extreme market pessimism regarding the company's outlook.
- Investor Rights Protection: Faruq & Faruqi encourages anyone with information regarding Mereo BioPharma's conduct, including whistleblowers and former employees, to contact the firm to provide legal support for affected investors, ensuring their rights are protected.
See More
Reminder of Class Action for Mereo BioPharma ADS Purchasers
- Class Action Notice: Rosen Law Firm reminds investors who purchased Mereo BioPharma ADS between June 5, 2023, and December 26, 2025, to apply as lead plaintiffs by April 6, 2026, to participate in the class action and seek compensation.
- Lawsuit Background: The lawsuit alleges that defendants provided false and misleading information regarding the Phase 3 Orbit and COSMIC studies, leading investors to purchase Mereo's ADS at artificially inflated prices, resulting in financial losses when the truth emerged.
- Law Firm's Advantage: Rosen Law Firm specializes in securities class actions and has recovered over $438 million for investors in 2019 alone, demonstrating its successful track record and extensive experience in this field.
- Investor Selection Advice: Investors are advised to carefully choose law firms with proven success in securities litigation to ensure effective legal support in class actions, avoiding firms that merely act as intermediaries.
See More
Mereo BioPharma Class Action Notice Issued
- Class Action Initiation: Rosen Law Firm reminds investors who purchased Mereo BioPharma ADS between June 5, 2023, and December 26, 2025, to apply as lead plaintiffs by April 6, 2026, to participate in the class action and potentially receive compensation without any out-of-pocket costs.
- Lawsuit Background: The lawsuit alleges that defendants provided false and misleading information regarding the expected results of the Phase 3 Orbit and COSMIC studies for setrusumab, leading investors to purchase Mereo's ADS at artificially inflated prices, resulting in financial losses when the truth emerged.
- Law Firm's Credentials: Rosen Law Firm specializes in securities class actions and has recovered over $438 million for investors in 2019 alone, being ranked first in 2017 for the number of securities class action settlements, showcasing its expertise in this field.
- Investor Advisory: Investors are advised to carefully select legal counsel, with Rosen Law Firm recommending choosing qualified attorneys with a proven track record in leadership roles to ensure optimal representation in the class action.
See More
Class Action Reminder for Mereo BioPharma Shareholders
- Lawsuit Background: Robbins LLP reminds all investors who purchased Mereo BioPharma Group plc (NASDAQ: MREO) American Depository Shares between June 5, 2023, and December 26, 2025, that a class action has been filed, alleging the company misled investors regarding the results of its drug studies.
- Study Failures: The complaint highlights that Mereo's Phase 3 ORBIT and COSMIC studies for Osteogenesis Imperfecta failed to meet their primary endpoint of reducing annualized fracture rates, despite the company's prior confidence, leading investors to buy shares at artificially inflated prices.
- Stock Price Plunge: On December 29, 2025, Mereo announced that its studies did not meet expectations, causing the stock price to plummet from $2.31 per share on December 26, 2025, to $0.29 per share, a decline of over 87.7%, severely impacting shareholder value.
- Opportunity to Participate: Shareholders wishing to serve as lead plaintiffs in the class action must submit their papers by April 6, 2026, indicating the importance of corporate governance and shareholder rights in the wake of such significant losses.
See More
Mereo BioPharma Class Action Notice Issued
- Class Action Deadline: Rosen Law Firm reminds investors who purchased Mereo BioPharma ADS between June 5, 2023, and December 26, 2025, that they must apply to be lead plaintiff by April 6, 2026, or risk losing their right to compensation, emphasizing the urgency for affected investors to act promptly.
- Cost Arrangement: Investors participating in the class action will incur no out-of-pocket fees, as attorney fees will be covered through a contingency fee arrangement, significantly lowering the financial barrier for investors to seek compensation and encouraging broader participation in the lawsuit.
- Lawsuit Background: The lawsuit alleges that Mereo BioPharma made false statements regarding the efficacy of setrusumab in its Phase 3 Orbit and COSMIC studies, leading investors to purchase ADS at artificially inflated prices, which resulted in significant losses when the truth was revealed, highlighting serious issues in the company's disclosure practices.
- Law Firm Credentials: Rosen Law Firm is recognized for its success in securities class actions, having recovered over $438 million for investors in 2019 alone, and was ranked first in 2017 for the number of securities class action settlements, demonstrating its expertise and influence in handling such cases effectively.
See More
Class Action Filed Against Mereo BioPharma Group plc
- Lawsuit Background: Bronstein, Gewirtz & Grossman LLC has filed a class action lawsuit against Mereo BioPharma Group plc, alleging violations of federal securities laws on behalf of all investors who purchased Mereo securities between June 5, 2023, and December 26, 2025.
- False Statements Allegation: The complaint claims that throughout the class period, defendants made overwhelmingly positive statements while disseminating materially false and misleading information, concealing adverse facts about the Phase 3 ORBIT and COSMIC programs, both of which failed to meet their primary endpoints for reducing clinical fracture rates.
- Investor Action: Affected investors are encouraged to apply to be lead plaintiffs by April 6, 2026, to share in any potential recovery, with the assurance that participation does not require serving as lead plaintiff.
- Law Firm's Advantage: Bronstein, Gewirtz & Grossman LLC operates on a contingency fee basis, having successfully recovered hundreds of millions for investors nationwide, emphasizing their expertise in securities fraud class actions and the importance of maintaining market integrity.
See More
Faruqi & Faruqi Investigates Mereo BioPharma for Securities Violations
- Legal Investigation Launched: Faruq & Faruqi LLP is investigating potential securities claims against Mereo BioPharma, specifically urging investors who purchased securities between June 5, 2023, and December 26, 2025, to contact them before the April 6, 2026, deadline to seek lead plaintiff status.
- Lawsuit Allegations Overview: The lawsuit alleges that Mereo and its executives violated federal securities laws by failing to disclose the true status of the Phase 3 ORBIT and COSMIC programs, both of which failed to meet their primary endpoints for reducing clinical fracture rates, resulting in significant investor losses.
- Stock Price Plunge Impact: Following Mereo's announcement on December 29, 2025, that both Phase 3 studies failed to meet primary endpoints, the stock price plummeted by $2.02, or 87.64%, closing at $0.28 per share, reflecting extreme market pessimism regarding the company's outlook.
- Investor Rights Protection: Faruq & Faruqi encourages anyone with information regarding Mereo BioPharma's conduct, including whistleblowers and former employees, to contact the firm to provide legal support for affected investors, ensuring their rights are protected.
See More
Reminder of Class Action for Mereo BioPharma ADS Purchasers
- Class Action Notice: Rosen Law Firm reminds investors who purchased Mereo BioPharma ADS between June 5, 2023, and December 26, 2025, to apply as lead plaintiffs by April 6, 2026, to participate in the class action and seek compensation.
- Lawsuit Background: The lawsuit alleges that defendants provided false and misleading information regarding the Phase 3 Orbit and COSMIC studies, leading investors to purchase Mereo's ADS at artificially inflated prices, resulting in financial losses when the truth emerged.
- Law Firm's Advantage: Rosen Law Firm specializes in securities class actions and has recovered over $438 million for investors in 2019 alone, demonstrating its successful track record and extensive experience in this field.
- Investor Selection Advice: Investors are advised to carefully choose law firms with proven success in securities litigation to ensure effective legal support in class actions, avoiding firms that merely act as intermediaries.
See More
Mereo BioPharma Class Action Notice Issued
- Class Action Initiation: Rosen Law Firm reminds investors who purchased Mereo BioPharma ADS between June 5, 2023, and December 26, 2025, to apply as lead plaintiffs by April 6, 2026, to participate in the class action and potentially receive compensation without any out-of-pocket costs.
- Lawsuit Background: The lawsuit alleges that defendants provided false and misleading information regarding the expected results of the Phase 3 Orbit and COSMIC studies for setrusumab, leading investors to purchase Mereo's ADS at artificially inflated prices, resulting in financial losses when the truth emerged.
- Law Firm's Credentials: Rosen Law Firm specializes in securities class actions and has recovered over $438 million for investors in 2019 alone, being ranked first in 2017 for the number of securities class action settlements, showcasing its expertise in this field.
- Investor Advisory: Investors are advised to carefully select legal counsel, with Rosen Law Firm recommending choosing qualified attorneys with a proven track record in leadership roles to ensure optimal representation in the class action.
See More
