<div id="readability-page-1"><div> <div> Did you buy RARE common stock between August 3, 2023, and December 26, 2025? Affected Ultragenyx Pharmaceutical Inc. Investor Summary <ul type="disc"> <li>Who: Ultragenyx Pharmaceutical Inc. (NASDAQ: RARE)</li> <li>What: Securities fraud class action lawsuit filed</li> <li>Class Period: August 3, 2023, through December 26, 2025</li> <li>Deadline to Seek Lead Plaintiff Status: April 6, 2026</li> <li>Key Lawsuit Allegations: Material misstatements and/or omissions concerning the company's drug, setrusumab</li> <li>Investor Action: Contact Kessler Topaz Meltzer &amp; Check, LLP (www.ktmc.com) for recovery options at no cost to investor</li> </ul> , /PRNewswire/ -- Kessler Topaz Meltzer &amp; Check, LLP (www.ktmc.com) informs investors that a securities fraud class action lawsuit has been filed against Ultragenyx Pharmaceutical Inc. (Ultragenyx) (NASDAQ: RARE) on behalf of those who purchased or acquired Ultragenyx common stock between August 3, 2023, and December 26, 2025, inclusive. The lawsuit is filed in the United States District Court for the Northern District of California and is captioned Bailey v. Ultragenyx Pharmaceutical Inc., et al, Case No. 3:26-cv-01097 (N.D. Cal.). Investors have until April 6, 2026, to file for lead plaintiff status. CONTACT KTMC TO DISCUSS YOUR LEGAL RIGHTS: If you purchased or acquired Ultragenyx Pharmaceutical Inc. common stock and have lost money on your investment, you are encouraged to contact KTMC attorney Jonathan Naji, Esq. at: 📞 (484) 270-1453 📧 [email protected] 🌐 https://www.ktmc.com/rare-ultragenyx-pharmaceutical-inc-class-action-lawsuit?utm_source=PR_Newswire&amp;utm_medium=pressrelease&amp;utm_campaign=rare&amp;mktm=PR There is no cost or obligation to speak with an attorney. Learn more about Ultragenyx Pharmaceutical Inc. on YouTube: <ul type="disc"> <li>Ultragenyx Pharmaceutical Inc. Securities Class Action Lawsuit (long video)</li> <li>Ultragenyx Pharmaceutical Inc. Securities Class Action Lawsuit (short video)</li> </ul> ULTRAGENYX PHARMACEUTICAL INC. CLASS ACTION LAWSUIT - COMPLAINT ALLEGATION SUMMARY: The complaint alleges that, throughout the Class Period, Defendants made false and/or misleading statements and/or failed to disclose that: (1) Ultragenyx created the false impression that they possessed reliable information pertaining to the effects of the company's drug, setrusumab, on patients with variable types of Osteogenesis Imperfecta, while also minimizing risk that patients in Ultragenyx's Phase III Orbit study would fail to achieve a statistically significant reduction in annualized fracture rate (&#34;AFR&#34;), such that the second interim analysis could be performed and presented to the investing public; (2) in truth, Ultragenyx's optimism in the Phase III Orbit study's results and interim analysis benchmark were misplaced because Ultragenyx failed to convey the risk associated with basing such threshold figures on Phase II results that had no placebo control group for appropriate comparison and thus had not ruled out that the reduction in AFR from that study could merely be triggered by an increased standard of care and the placebo effect of being provided a novel treatment; and (3) as a result, Defendants' positive statements about the company's business, operations, and prospects were materially misleading and/or lacked a reasonable basis. Why did Ultragenyx's Stock Drop? On December 29, 2025, Ultragenyx shocked the market when it revealed that both its Phase III Orbit and Cosmic studies had not &#34;achieved statistical significance against the primary endpoints of reduction in annualized clinical fracture rate compared to placebo or bisphosphonates, respectively.&#34; On this news, Ultragenyx's stock price fell over 42%, from a close of $34.19 per share on December 26, 2025, to close at $19.72 per share on December 29, 2025. WHAT RARE INVESTORS CAN DO NOW: <ol type="1"> <li>File to be lead plaintiff by April 6, 2026.</li> <li>Contact KTMC for a free case evaluation.</li> <li>Retain counsel of choice or take no action.</li> </ol> THE LEAD PLAINTIFF PROCESS FOR ULTRAGENYX PHARMACEUTICAL INC. INVESTORS: Ultragenyx investors may, no later than April 6, 2026, seek to be appointed as a lead plaintiff representative of the class through Kessler Topaz Meltzer &amp; Check, LLP or other counsel, or may choose to do nothing and remain an absent class member. A lead plaintiff is a representative party who acts on behalf of all class members in directing the litigation. The lead plaintiff is usually the investor or small group of investors who have the largest financial interest and who are also adequate and typical of the proposed class of investors. The lead plaintiff selects counsel to represent the lead plaintiff and the class and these attorneys, if approved by the court, are lead or class counsel. Your ability to share in any recovery is not affected by the decision of whether or not to serve as a lead plaintiff. Kessler Topaz Meltzer &amp; Check, LLP encourages Ultragenyx investors to contact the firm for more information. ABOUT KESSLER TOPAZ MELTZER &amp; CHECK, LLP (KTMC): Kessler Topaz Meltzer &amp; Check, LLP (KTMC) is a leading U.S. plaintiff-side law firm focused on securities-fraud class actions and global investor protection. The firm represents individual investors as well as institutions, such as major pension funds, asset managers, and international investors. KTMC has led some of the largest recoveries in securities litigation and has been recognized by peers and the legal media with numerous accolades, including The National Law Journal's Plaintiff's Hot List and Trailblazers in Plaintiffs' Law, BTI Consulting Group's Honor Roll of Most Feared Law Firms, The Legal Intelligencer's Class Action Firm of the Year, Lawdragon's Leading Plaintiff Financial Lawyers, and Law360's Titans of the Plaintiffs Bar. The firm operates globally with offices in Pennsylvania and California. KTMC has recovered over $25 billion for our clients and the classes they represent. For more information about Kessler Topaz Meltzer &amp; Check, LLP, please visit www.ktmc.com. The complaint in this matter was not filed by KTMC. CONTACT: Jonathan Naji, Esq. (484) 270-1453 280 King of Prussia Road Radnor, PA 19087 [email protected] May be considered attorney advertising in certain jurisdictions. Past results do not guarantee future outcomes. SOURCE Kessler Topaz Meltzer &amp; Check, LLP <img src="https://imageproxy.pbkrs.com/https://rt.prnewswire.com/rt.gif/query-RGF0ZUlkPTIwMjYwMzA4Jk5ld3NJdGVtSWQ9REMwMjk2MyZUcmFuc21pc3Npb25fSWQ9MjAyNjAzMDgxMjAwUFJfTkVXU19VU1BSX19fX19EQzAyOTYz?x-oss-process=image/auto-orient,1/interlace,1/resize,w_1440,h_1440/quality,q_95/format,jpg" original-src="https://imageproxy.pbkrs.com/https://rt.prnewswire.com/rt.gif/query-RGF0ZUlkPTIwMjYwMzA4Jk5ld3NJdGVtSWQ9REMwMjk2MyZUcmFuc21pc3Npb25fSWQ9MjAyNjAzMDgxMjAwUFJfTkVXU19VU1BSX19fX19EQzAyOTYz"/></div> </div></div>

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Kessler Topaz Meltzer & Check, LLP has announced a securities fraud class action lawsuit against Ultragenyx Pharmaceutical Inc. (NASDAQ: RARE) for investors who purchased shares between August 3, 2023, and December 26, 2025. The lawsuit alleges material misstatements regarding the company's drug, setrusumab, and investors have until April 6, 2026, to seek lead plaintiff status. Following the announcement of disappointing Phase III study results, Ultragenyx's stock price dropped over 42%. Affected investors are encouraged to contact KTMC for recovery options at no cost.

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12:00 ETRARE Investor Alert: Kessler Topaz Meltzer & Check, LLP Encourages RARE Investors with Losses to Contact the Firm