LEVI & KORSINSKY, LLP: FRAUD-ON-THE-MARKET DOCTRINE UNDERPINS ULTRAGENYX PHARMACEUTICAL SECURITIES CLASS ACTION

Know Your Rights: How Basic Inc. v. Levinson Enables Investor Recovery

NEW YORK, March 18, 2026 /PRNewswire/ -- Levi & Korsinsky, LLP announces that a securities class action has been filed against Ultragenyx Pharmaceutical Inc. (NASDAQ: RARE).

YOU MAY BE AFFECTED IF YOU:

• Purchased Ultragenyx stock between August 3, 2023 and December 26, 2025
• Lost money on your Ultragenyx investment

The Efficient Market Hypothesis

In Basic Inc. v. Levinson, 485 U.S. 224 (1988), the Supreme Court recognized that in an efficient market, publicly available information is rapidly incorporated into stock prices. This means that when a company makes materially false or misleading statements, the artificial inflation caused by those statements is embedded in the stock price---even if individual investors did not directly read or hear the false statements. The action alleges that Ultragenyx's stock traded in such an efficient market during the Class Period.

The Fraud-on-the-Market Doctrine

• Basic Inc. v. Levinson established the fraud-on-the-market presumption of reliance for securities class actions
• Under this doctrine, investors who trade in an efficient market are presumed to rely on the integrity of the market price
• Halliburton Co. v. Erica P. John Fund, Inc. (2014) reaffirmed the fraud-on-the-market presumption
• Plaintiffs contend this framework enables class-wide adjudication of alleged securities fraud claims
• The presumption allows investors to pursue claims without proving individual reliance on each false statement

Learn more about your rights or contact Joseph E. Levi, Esq. at [email protected] | (212) 363-7500.

Application to Ultragenyx

The action alleges that Ultragenyx common stock traded on the NASDAQ during the Class Period, a highly efficient and automated market. Plaintiffs contend that the Company communicated with investors through established market mechanisms, including SEC filings, press releases, and earnings calls, and that the stock was followed by securities analysts whose reports were publicly available.

Rule 23 Class Certification

Federal Rule of Civil Procedure 23 governs class certification requirements. The action alleges that common questions of law and fact predominate over individual issues, making class treatment superior to individual litigation. These common questions include whether defendants' statements were materially false or misleading and whether the stock price was artificially inflated.

"Securities class actions allow investors to efficiently pursue claims that might otherwise be too costly to bring individually," said Joseph E. Levi, Esq. "The legal framework supports investor recovery when fraud is alleged."

Join the Ultragenyx class action or call (212) 363-7500.

ABOUT THE FIRM

Levi & Korsinsky, LLP represents investors in securities class actions nationwide, with particular expertise in complex fraud-on-the-market cases and Section 10(b) litigation. The firm has been ranked among ISS Securities Class Action Services' Top 50 for seven consecutive years. Lead plaintiff applications must be submitted by April 6, 2026.

CONTACT:
Levi & Korsinsky, LLP
Joseph E. Levi, Esq.
33 Whitehall Street, 27th Floor
New York, NY 10004
(212) 363-7500
[email protected]
www.zlk.com

SOURCE Levi & Korsinsky, LLP