Class Action Lawsuit Filed Against Ultragenyx Pharmaceutical Inc.
Written by Emily J. Thompson, Senior Investment Analyst
Updated: Feb 08 2026
0mins
Should l Buy RARE?
Source: Globenewswire
- Lawsuit Background: Bronstein, Gewirtz & Grossman, LLC, a nationally recognized investor-rights law firm, has filed a class action lawsuit against Ultragenyx Pharmaceutical Inc. (NASDAQ: RARE) and certain officers, seeking damages for investors who acquired Ultragenyx securities between August 3, 2023, and December 26, 2025.
- False Statements Allegation: The complaint alleges that throughout the class period, defendants made false and/or misleading statements and failed to disclose risks associated with the Phase III Orbit study for Osteogenesis Imperfecta (OI), leading investors to have an unwarranted optimistic view of the study's results.
- 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 Reputation: Bronstein, Gewirtz & Grossman, LLC is well-regarded in securities fraud class actions, having recovered hundreds of millions for investors nationwide, emphasizing its commitment to restoring investor capital and ensuring corporate accountability.
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Analyst Views on RARE
Wall Street analysts forecast RARE stock price to rise
18 Analyst Rating
17 Buy
1 Hold
0 Sell
Strong Buy
Current: 22.610
Low
35.00
Averages
61.65
High
120.00
Current: 22.610
Low
35.00
Averages
61.65
High
120.00
About RARE
Ultragenyx Pharmaceutical Inc. is a biopharmaceutical company. The Company is focused on the identification, acquisition, development, and commercialization of novel products for the treatment of serious rare and ultrarare genetic diseases. Its therapies and clinical-stage pipeline consist of four product categories: biologics, small molecules, AAV gene therapy, and nucleic acid product candidates. Its four approved product candidates include Crysvita (burosumab) for the treatment of X-linked hypophosphatemia (XLH), and tumor-induced osteomalacia (TIO), Mepsevii (vestronidase alfa) for the treatment of mucopolysaccharidosis VII (MPSVII) or Sly Syndrome, Dojolvi (triheptanoin) for the treatment of long-chain fatty acid oxidation disorders (LC-FAOD), and Evkeeza (evinacumab) for the treatment of homozygous familial hypercholesterolemia (HoFH). Its clinical product candidates include DTX401, DTX301, UX701, UX143, UX111, and GTX-102. UX143 for the treatment of Osteogenesis Imperfecta.
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.
Ultragenyx Pharmaceutical Class Action Notice
- Class Action Deadline: Ultragenyx Pharmaceutical Inc. (NASDAQ:RARE) reminds stock purchasers from August 3, 2023, to December 26, 2025, that the lead plaintiff deadline is April 6, 2026, and failure to act may result in loss of participation rights.
- Fee Arrangement: Investors joining the class action can seek compensation without upfront costs through a contingency fee arrangement, which alleviates financial burdens and encourages affected shareholders to participate in the litigation.
- Lawsuit Background: The lawsuit alleges that Ultragenyx misled investors regarding the expected results of its studies for Osteogenesis Imperfecta, providing overly optimistic projections while concealing critical adverse information, leading shareholders to purchase stock at inflated prices.
- Counsel Selection: The Rosen Law Firm emphasizes the importance of selecting qualified counsel with a proven track record, noting that many firms issuing notices lack the necessary litigation experience and resources, urging investors to choose their representatives wisely.
See More
Ultragenyx Pharmaceutical Class Action Reminder
- Class Action Notice: Rosen Law Firm reminds investors who purchased Ultragenyx Pharmaceutical (NASDAQ: RARE) common stock between August 3, 2023, and December 26, 2025, to apply as lead plaintiffs by April 6, 2026, to potentially receive compensation without any out-of-pocket costs.
- Lawsuit Background: The lawsuit alleges that defendants misled investors regarding the efficacy of setrusumab (UX 143) in treating Osteogenesis Imperfecta (OI) by concealing adverse information, resulting in shareholders purchasing stock at artificially inflated prices and suffering losses when the truth emerged.
- Law Firm Credentials: Rosen Law Firm specializes in securities class actions and has recovered over $438 million for investors in 2019 alone, being ranked first by ISS Securities Class Action Services in 2017, highlighting its strong track record and expertise in this area.
- Investor Action Advice: Investors can visit Rosen Law Firm's website or call the toll-free number for more information, ensuring they select qualified legal counsel to represent them effectively in the lawsuit and avoid inexperienced intermediaries.
See More
Ultragenyx Faces Class Action Over Misleading Drug Information
- Class Action Notification: The Portnoy Law Firm advises Ultragenyx Pharmaceutical investors of a class action for those who purchased securities between August 3, 2023, and December 26, 2025, with a deadline for lead plaintiff motions set for April 6, 2026, highlighting the urgency for affected investors to act.
- False Statement Allegations: The lawsuit alleges that Ultragenyx misled investors regarding the efficacy of its drug setrusumab, failing to disclose risks that patients in the Phase III Orbit study might not achieve a statistically significant reduction in annualized fracture rate, which misrepresented the company's prospects and misled investment decisions.
- Clinical Trial Risks: Ultragenyx's failure to adequately communicate the risks associated with relying on Phase II results without a placebo control group raises concerns about the validity of their optimistic claims regarding the drug's effectiveness, potentially undermining investor confidence in the company's operations.
- Legal Consultation Services: The Portnoy Law Firm offers complimentary case evaluations and encourages investors to reach out to discuss their legal options for recovering losses, demonstrating the firm's commitment to protecting investor rights and providing support in the face of corporate misconduct.
See More
Ultragenyx and Mereo BioPharma Class Action Reminder
- Lawsuit Initiation: Bragar Eagel & Squire law firm has commenced class actions on behalf of shareholders of Ultragenyx Pharmaceutical (NASDAQ:RARE) and Mereo BioPharma (NASDAQ:MREO), with a lead plaintiff deadline of April 6, 2026, indicating significant investor concern regarding potential risks associated with these companies.
- Study Result Failures: On December 29, 2025, Ultragenyx announced that its Phase III Orbit and Cosmic studies failed to achieve statistical significance in reducing annualized fracture rates, causing its stock price to plummet by approximately 42.32% in a single day, from $34.19 to $19.72, reflecting market disappointment in the study outcomes.
- Mereo BioPharma's Reaction: Similarly, Mereo BioPharma announced on December 29, 2025, that its ORBIT and COSMIC studies did not meet the primary endpoint of reducing annualized clinical fracture rates, despite improved bone mineral density, leading to a dramatic decline in its ADS price from $2.31 to $0.29, a drop of over 87.7%, highlighting severe investor confidence erosion.
- Disclosure Issues: The lawsuits allege that both companies provided overly optimistic projections to investors while concealing significant adverse facts related to the study protocols, resulting in shareholders purchasing stocks at artificially inflated prices, raising concerns about corporate governance and transparency.
See More
Ultragenyx Pharmaceutical Faces Securities Fraud Class Action Lawsuit
- Lawsuit Background: Kessler Topaz Meltzer & Check, LLP has filed a securities fraud class action against Ultragenyx Pharmaceutical on behalf of investors who purchased shares between August 3, 2023, and December 26, 2025, highlighting serious concerns regarding the company's transparency and communication.
- Stock Price Plunge: On December 29, 2025, Ultragenyx shocked the market by revealing that its clinical trials failed to achieve statistical significance, causing its stock price to plummet 42% from $34.19 to $19.72, indicating a significant loss of investor confidence in the company's future prospects.
- Investor Rights: Investors are encouraged to apply for lead plaintiff status by April 6, 2026, to represent the class in the lawsuit, emphasizing the importance of investor agency and potential financial recovery in legal proceedings.
- Law Firm's Role: Kessler Topaz Meltzer & Check, LLP is a leading law firm specializing in securities fraud litigation, having recovered over $25 billion for clients and represented significant institutional investors, showcasing its strength and influence in the investor protection landscape.
See More
Class Action Lawsuit Filed Against Ultragenyx Pharmaceutical Inc.
- Lawsuit Background: Bronstein, Gewirtz & Grossman, LLC has filed a class action lawsuit against Ultragenyx Pharmaceutical Inc. and certain officers, seeking damages for investors who purchased securities between August 3, 2023, and December 26, 2025, reflecting significant investor dissatisfaction with the company's transparency.
- False Statement Allegations: The complaint alleges that throughout the class period, defendants made false and/or misleading statements and failed to disclose risks associated with the Phase III Orbit study on Osteogenesis Imperfecta patients, potentially misleading investors and impacting stock prices.
- Investor Action: Affected investors are encouraged to apply to be lead plaintiffs by April 6, 2026, to share in any potential recovery, indicating growing concerns among investors regarding corporate governance and information disclosure.
- Law Firm's Advantage: Bronstein, Gewirtz & Grossman, LLC has extensive experience in securities fraud class actions, having recovered hundreds of millions for investors nationwide, emphasizing their expertise in restoring investor capital and ensuring corporate accountability, which may bolster investor confidence in the lawsuit's outcome.
See More
Ultragenyx Pharmaceutical Class Action Notice
- Class Action Deadline: Ultragenyx Pharmaceutical Inc. (NASDAQ:RARE) reminds stock purchasers from August 3, 2023, to December 26, 2025, that the lead plaintiff deadline is April 6, 2026, and failure to act may result in loss of participation rights.
- Fee Arrangement: Investors joining the class action can seek compensation without upfront costs through a contingency fee arrangement, which alleviates financial burdens and encourages affected shareholders to participate in the litigation.
- Lawsuit Background: The lawsuit alleges that Ultragenyx misled investors regarding the expected results of its studies for Osteogenesis Imperfecta, providing overly optimistic projections while concealing critical adverse information, leading shareholders to purchase stock at inflated prices.
- Counsel Selection: The Rosen Law Firm emphasizes the importance of selecting qualified counsel with a proven track record, noting that many firms issuing notices lack the necessary litigation experience and resources, urging investors to choose their representatives wisely.
See More
Ultragenyx Pharmaceutical Class Action Reminder
- Class Action Notice: Rosen Law Firm reminds investors who purchased Ultragenyx Pharmaceutical (NASDAQ: RARE) common stock between August 3, 2023, and December 26, 2025, to apply as lead plaintiffs by April 6, 2026, to potentially receive compensation without any out-of-pocket costs.
- Lawsuit Background: The lawsuit alleges that defendants misled investors regarding the efficacy of setrusumab (UX 143) in treating Osteogenesis Imperfecta (OI) by concealing adverse information, resulting in shareholders purchasing stock at artificially inflated prices and suffering losses when the truth emerged.
- Law Firm Credentials: Rosen Law Firm specializes in securities class actions and has recovered over $438 million for investors in 2019 alone, being ranked first by ISS Securities Class Action Services in 2017, highlighting its strong track record and expertise in this area.
- Investor Action Advice: Investors can visit Rosen Law Firm's website or call the toll-free number for more information, ensuring they select qualified legal counsel to represent them effectively in the lawsuit and avoid inexperienced intermediaries.
See More
Ultragenyx Faces Class Action Over Misleading Drug Information
- Class Action Notification: The Portnoy Law Firm advises Ultragenyx Pharmaceutical investors of a class action for those who purchased securities between August 3, 2023, and December 26, 2025, with a deadline for lead plaintiff motions set for April 6, 2026, highlighting the urgency for affected investors to act.
- False Statement Allegations: The lawsuit alleges that Ultragenyx misled investors regarding the efficacy of its drug setrusumab, failing to disclose risks that patients in the Phase III Orbit study might not achieve a statistically significant reduction in annualized fracture rate, which misrepresented the company's prospects and misled investment decisions.
- Clinical Trial Risks: Ultragenyx's failure to adequately communicate the risks associated with relying on Phase II results without a placebo control group raises concerns about the validity of their optimistic claims regarding the drug's effectiveness, potentially undermining investor confidence in the company's operations.
- Legal Consultation Services: The Portnoy Law Firm offers complimentary case evaluations and encourages investors to reach out to discuss their legal options for recovering losses, demonstrating the firm's commitment to protecting investor rights and providing support in the face of corporate misconduct.
See More
Ultragenyx and Mereo BioPharma Class Action Reminder
- Lawsuit Initiation: Bragar Eagel & Squire law firm has commenced class actions on behalf of shareholders of Ultragenyx Pharmaceutical (NASDAQ:RARE) and Mereo BioPharma (NASDAQ:MREO), with a lead plaintiff deadline of April 6, 2026, indicating significant investor concern regarding potential risks associated with these companies.
- Study Result Failures: On December 29, 2025, Ultragenyx announced that its Phase III Orbit and Cosmic studies failed to achieve statistical significance in reducing annualized fracture rates, causing its stock price to plummet by approximately 42.32% in a single day, from $34.19 to $19.72, reflecting market disappointment in the study outcomes.
- Mereo BioPharma's Reaction: Similarly, Mereo BioPharma announced on December 29, 2025, that its ORBIT and COSMIC studies did not meet the primary endpoint of reducing annualized clinical fracture rates, despite improved bone mineral density, leading to a dramatic decline in its ADS price from $2.31 to $0.29, a drop of over 87.7%, highlighting severe investor confidence erosion.
- Disclosure Issues: The lawsuits allege that both companies provided overly optimistic projections to investors while concealing significant adverse facts related to the study protocols, resulting in shareholders purchasing stocks at artificially inflated prices, raising concerns about corporate governance and transparency.
See More
Ultragenyx Pharmaceutical Faces Securities Fraud Class Action Lawsuit
- Lawsuit Background: Kessler Topaz Meltzer & Check, LLP has filed a securities fraud class action against Ultragenyx Pharmaceutical on behalf of investors who purchased shares between August 3, 2023, and December 26, 2025, highlighting serious concerns regarding the company's transparency and communication.
- Stock Price Plunge: On December 29, 2025, Ultragenyx shocked the market by revealing that its clinical trials failed to achieve statistical significance, causing its stock price to plummet 42% from $34.19 to $19.72, indicating a significant loss of investor confidence in the company's future prospects.
- Investor Rights: Investors are encouraged to apply for lead plaintiff status by April 6, 2026, to represent the class in the lawsuit, emphasizing the importance of investor agency and potential financial recovery in legal proceedings.
- Law Firm's Role: Kessler Topaz Meltzer & Check, LLP is a leading law firm specializing in securities fraud litigation, having recovered over $25 billion for clients and represented significant institutional investors, showcasing its strength and influence in the investor protection landscape.
See More
Class Action Lawsuit Filed Against Ultragenyx Pharmaceutical Inc.
- Lawsuit Background: Bronstein, Gewirtz & Grossman, LLC has filed a class action lawsuit against Ultragenyx Pharmaceutical Inc. and certain officers, seeking damages for investors who purchased securities between August 3, 2023, and December 26, 2025, reflecting significant investor dissatisfaction with the company's transparency.
- False Statement Allegations: The complaint alleges that throughout the class period, defendants made false and/or misleading statements and failed to disclose risks associated with the Phase III Orbit study on Osteogenesis Imperfecta patients, potentially misleading investors and impacting stock prices.
- Investor Action: Affected investors are encouraged to apply to be lead plaintiffs by April 6, 2026, to share in any potential recovery, indicating growing concerns among investors regarding corporate governance and information disclosure.
- Law Firm's Advantage: Bronstein, Gewirtz & Grossman, LLC has extensive experience in securities fraud class actions, having recovered hundreds of millions for investors nationwide, emphasizing their expertise in restoring investor capital and ensuring corporate accountability, which may bolster investor confidence in the lawsuit's outcome.
See More
