Cases
Ultragenyx Pharmaceutical Inc.
Securities Class Action
Overview
Overview
- Date:
- 4/6/2026
- Company Name:
- Ultragenyx Pharmaceutical Inc.
- Stock Symbol:
- RARE
- Class Period:
- FROM 8/3/2023 TO 12/26/2025
- Status:
- Filed
- Filing Date:
- 2/4/2026
- Court:
- U.S. District Court: Northern California
Bragar Eagel & Squire, P.C., a nationally recognized stockholder rights law firm, announces that a class action lawsuit has been filed against Ultragenyx Pharmaceutical Inc. (“Ultragenyx” or the “Company”) (NASDAQ:RARE) in the United States District Court for the Northern District of California on behalf of all persons and entities who purchased or otherwise acquired Ultragenyx common stock between August 3, 2023, to December 26, 2025, both dates inclusive (the “Class Period”). Investors have until April 6, 2026 to apply to the Court to be appointed as lead plaintiff in the lawsuit.
According to the complaint, during the class period, defendants provided investors with material information concerning Ultragenyx’s expected results for its Phase III Orbit and Cosmic Studies, which tested setrusumab (UX 143) in patients with Osteogenesis Imperfecta (“OI”). Defendants’ statements included, among other things, confidence in setrusumab’s ability to ultimately trigger a decrease in the OI patients’ annualized fracture rate, alongside confidence in the study designs to demonstrate such ability and reduce testing variability that could interfere with such a result.
Plaintiff alleges that defendants provided these 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 setrusumab’s potential and the true risk inherent in the study protocols put forth; notably, that, while setrusumab does increase material bone density, this increase does not correlate to a decrease in annualized fracture rates or otherwise the Phase III Orbit and Cosmic studies were much less likely to be able to demonstrate such a link than management claimed. Such statements absent these material facts caused Plaintiff and other shareholders to purchase Ultragenyx’s securities at artificially inflated prices.
The complaint alleges that on December 29, 2025, Ultragenyx announced that both its Phase III Orbit and Cosmic Studies had not “achieved statistical significance against the primary endpoints of reduction in annualized clinical fracture rate compared to placebo or bisphosphonates, respectively.” The Company attributed the study failure to a “low fracture rate in the placebo group” of Orbit and a trend that fell shy of statistical significance in Cosmic. On this news, the price of Ultragenyx's stock fell from a closing market price of $34.19 per share on December 26, 2025, to $19.72 per share on December 29, 2025, a decline of about 42.32% in the span of just a single day.
If you purchased or otherwise acquired Ultragenyx shares and suffered a loss, are a long-term stockholder, have information, would like to learn more about these claims, or have any questions concerning this announcement or your rights or interests with respect to these matters, please contact Brandon Walker or Melissa Fortunato by email at investigations@bespc.com, telephone at (212) 355-4648, or by filling out the form below. There is no cost or obligation to you.
According to the complaint, during the class period, defendants provided investors with material information concerning Ultragenyx’s expected results for its Phase III Orbit and Cosmic Studies, which tested setrusumab (UX 143) in patients with Osteogenesis Imperfecta (“OI”). Defendants’ statements included, among other things, confidence in setrusumab’s ability to ultimately trigger a decrease in the OI patients’ annualized fracture rate, alongside confidence in the study designs to demonstrate such ability and reduce testing variability that could interfere with such a result.
Plaintiff alleges that defendants provided these 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 setrusumab’s potential and the true risk inherent in the study protocols put forth; notably, that, while setrusumab does increase material bone density, this increase does not correlate to a decrease in annualized fracture rates or otherwise the Phase III Orbit and Cosmic studies were much less likely to be able to demonstrate such a link than management claimed. Such statements absent these material facts caused Plaintiff and other shareholders to purchase Ultragenyx’s securities at artificially inflated prices.
The complaint alleges that on December 29, 2025, Ultragenyx announced that both its Phase III Orbit and Cosmic Studies had not “achieved statistical significance against the primary endpoints of reduction in annualized clinical fracture rate compared to placebo or bisphosphonates, respectively.” The Company attributed the study failure to a “low fracture rate in the placebo group” of Orbit and a trend that fell shy of statistical significance in Cosmic. On this news, the price of Ultragenyx's stock fell from a closing market price of $34.19 per share on December 26, 2025, to $19.72 per share on December 29, 2025, a decline of about 42.32% in the span of just a single day.
If you purchased or otherwise acquired Ultragenyx shares and suffered a loss, are a long-term stockholder, have information, would like to learn more about these claims, or have any questions concerning this announcement or your rights or interests with respect to these matters, please contact Brandon Walker or Melissa Fortunato by email at investigations@bespc.com, telephone at (212) 355-4648, or by filling out the form below. There is no cost or obligation to you.
Contact Instructions
Please contact Brandon Walker or Melissa Fortunato by email at investigations@bespc.com with any questions.
The individual or institution below (“Plaintiff”) has reviewed and agrees to the Bragar Eagel & Squire, P.C. (“BESPC”) retainer agreement and authorizes BESPC to prosecute an action on Plaintiff’s behalf under the federal securities laws or applicable state laws to recover damages on behalf of investors in Ultragenyx Pharmaceutical Inc. . BESPC will prosecute the action on a full contingency basis and will forward all costs and expenses.
Case Updates
Retainer Agreement
This will confirm that you have retained Bragar Eagel & Squire, P.C. (“BESPC”) to represent you in connection with potential litigation against Ultragenyx Pharmaceutical Inc. (the “Company”) and its directors and officers. BESPC has conducted an investigation and believes that there is a valid basis to assert claims against the Company and its directors and/or officers for violation of federal or state securities laws.
In making this agreement, BESPC is relying upon your representation that you purchased the Company’s shares during the period from 8/3/2023 to 12/26/2025 (the “Relevant Period”). Please provide us with documentation of your trading history in the Company’s stock by emailing a relevant copies of your brokerage statements to investigations@bespc.com. If you have any questions or need assistance, please call us at (212) 308-5858.
The terms under which we will represent you and your responsibilities as a potential representative plaintiff are set forth below.
You will have an obligation to remain knowledgeable about the litigation and participate in decisions concerning the progress of the litigation. If BESPC is appointed as lead counsel or in a similar capacity in the action, we will provide you with copies of all pleadings in the litigation for your review and approval, circumstances permitting, before they are filed with the court. BESPC will also promptly advise you of any significant developments in the litigation.
As a representative plaintiff, you cannot have any interest antagonistic to or in conflict with other Class members or the Company, as applicable, concerning the claims we are pursuing or any relationships with any of the named defendants that would in any way impair your ability or incentive to obtain the best possible result. You agree that neither you nor any of your affiliates or agents will trade stocks while in the possession of any material non-public information you may receive in connection with the litigation. In addition, as a representative plaintiff, you may be required to continue holding Company shares. Please contact us before buying or selling Company shares.
BESPC may associate with other counsel to assist in the prosecution of this litigation. Any recovery of fees and costs will be shared with such counsel, determined on a percentage basis or based upon the time spent on the matter, as approved by the court if applicable. The division of work and or fees among co-counsel will not affect the amount of fees received upon a successful completion of the litigation. From time to time, BESPC may utilize contract attorneys to supplement the work of its own employed attorneys. BESPC will supervise the work of all contract attorneys and adopt their work product as its own. You authorize BESPC, as we deem appropriate, to associate with other counsel and to hire experts and consultants to assist in the handling of your claims.
It is possible that you will not be appointed as a lead plaintiff or class representative in the action. However, we may wish to represent you in other litigation related to the wrongful acts giving rise to this case. In such event, we will contact you to discuss the scope of such representation and obtain your approval before moving forward. You also agree that we may contact you with respect to other potential matters on your behalf.
You understand that in the event we secure a recovery for a Class in a class action, you will only be entitled to your proportional share of such recovery as a Class member. You understand that you will not receive any special treatment or receive a greater share of any class-wide recovery based on your service as a named plaintiff or class representative. However, we may ask the Court to approve an additional award to you to compensate you for the time and effort you expend on this matter. Any such award is solely within the discretion of the Court.
BESPC will consult with you regarding any settlement negotiations and seek to obtain your approval for any proposed resolution of this litigation before entering into a final settlement agreement with defendants.
You expressly acknowledge that we have not made any representation to you, express or implied, concerning the outcome of any litigation or other matter in which we represent you.
If you are not chosen as a representative plaintiff and we do not choose to pursue other related litigation on your behalf, we will provide you with notification and this Agreement shall terminate. Otherwise, this Agreement shall remain in effect until the conclusion of the relevant litigation. However, you may terminate this Agreement at any time.
Upon termination, BESPC’s files and papers compiled in connection with its investigation and prosecution of this matter constitute the work product and property of BESPC over which it has complete control with respect to its use and/or disclosure.
This agreement sets forth the entire agreement between the parties and supersedes all other oral or written communications.
Please feel free to contact us at any time should you have any questions or comments in this regard.
In making this agreement, BESPC is relying upon your representation that you purchased the Company’s shares during the period from 8/3/2023 to 12/26/2025 (the “Relevant Period”). Please provide us with documentation of your trading history in the Company’s stock by emailing a relevant copies of your brokerage statements to investigations@bespc.com. If you have any questions or need assistance, please call us at (212) 308-5858.
The terms under which we will represent you and your responsibilities as a potential representative plaintiff are set forth below.
Your Responsibilities as a Representative Plaintiff
As a representative plaintiff, you will have a duty to represent the interests of similarly situated shareholders, i.e., the “Class,” and to participate in the prosecution of this litigation. You may also be asked to provide documents concerning your trading in Company stock and may be asked to sit for a deposition. Accordingly, you should preserve all documents that relate to this case until it has concluded or we inform you otherwise. Relevant documents include any information you have about the Company or your trading in Company stock, no matter how it is recorded or who is keeping it for you. If you have any questions about whether information should be retained, please contact us.You will have an obligation to remain knowledgeable about the litigation and participate in decisions concerning the progress of the litigation. If BESPC is appointed as lead counsel or in a similar capacity in the action, we will provide you with copies of all pleadings in the litigation for your review and approval, circumstances permitting, before they are filed with the court. BESPC will also promptly advise you of any significant developments in the litigation.
As a representative plaintiff, you cannot have any interest antagonistic to or in conflict with other Class members or the Company, as applicable, concerning the claims we are pursuing or any relationships with any of the named defendants that would in any way impair your ability or incentive to obtain the best possible result. You agree that neither you nor any of your affiliates or agents will trade stocks while in the possession of any material non-public information you may receive in connection with the litigation. In addition, as a representative plaintiff, you may be required to continue holding Company shares. Please contact us before buying or selling Company shares.
Contingency Fee and Advancement of Expenses
BESPC will prosecute this litigation on a contingency basis. You will not be responsible for paying any legal fees, costs, or out-of-pocket expenses arising out of or related to the prosecution of this litigation, regardless of the outcome of the matter. If there is a monetary recovery in this action, BESPC will, at the conclusion of the litigation or any segment thereof, apply to the court for approval of an award of attorneys’ fees and reimbursement of expenses. BESPC may also seek a fee if we obtain substantial non-monetary relief for the Class or the Company. The court will then award fees and disbursements (if any) from the proceeds of any judgment or settlement obtained in this litigation, based on factors considered relevant by the court. Such fees, costs, and disbursements will be paid from the entire settlement amount and not only from your share of the settlement amount.
Association with Counsel
BESPC may associate with other counsel to assist in the prosecution of this litigation. Any recovery of fees and costs will be shared with such counsel, determined on a percentage basis or based upon the time spent on the matter, as approved by the court if applicable. The division of work and or fees among co-counsel will not affect the amount of fees received upon a successful completion of the litigation. From time to time, BESPC may utilize contract attorneys to supplement the work of its own employed attorneys. BESPC will supervise the work of all contract attorneys and adopt their work product as its own. You authorize BESPC, as we deem appropriate, to associate with other counsel and to hire experts and consultants to assist in the handling of your claims.
Other Actions
It is possible that you will not be appointed as a lead plaintiff or class representative in the action. However, we may wish to represent you in other litigation related to the wrongful acts giving rise to this case. In such event, we will contact you to discuss the scope of such representation and obtain your approval before moving forward. You also agree that we may contact you with respect to other potential matters on your behalf.
No Special Treatment
You understand that in the event we secure a recovery for a Class in a class action, you will only be entitled to your proportional share of such recovery as a Class member. You understand that you will not receive any special treatment or receive a greater share of any class-wide recovery based on your service as a named plaintiff or class representative. However, we may ask the Court to approve an additional award to you to compensate you for the time and effort you expend on this matter. Any such award is solely within the discretion of the Court.
Settlement
BESPC will consult with you regarding any settlement negotiations and seek to obtain your approval for any proposed resolution of this litigation before entering into a final settlement agreement with defendants.
No Guarantee of Success
You expressly acknowledge that we have not made any representation to you, express or implied, concerning the outcome of any litigation or other matter in which we represent you.
Termination of This Agreement
If you are not chosen as a representative plaintiff and we do not choose to pursue other related litigation on your behalf, we will provide you with notification and this Agreement shall terminate. Otherwise, this Agreement shall remain in effect until the conclusion of the relevant litigation. However, you may terminate this Agreement at any time. Upon termination, BESPC’s files and papers compiled in connection with its investigation and prosecution of this matter constitute the work product and property of BESPC over which it has complete control with respect to its use and/or disclosure.
This agreement sets forth the entire agreement between the parties and supersedes all other oral or written communications.
Please feel free to contact us at any time should you have any questions or comments in this regard.