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benzinga Corporate Catalyst Impact 95/100 ● positive

Ultragenyx Pharmaceutical (RARE) Stock Jumps After Hours: Here's Why It Is Trending

Sep 18, 2026, 4:26 AM UTC · Primary ticker $RARE

Ultragenyx Pharmaceutical received full FDA approval for FAYUVI, the first treatment for Sanfilippo syndrome Type A, an ultra-rare and fatal childhood disease. This approval is a significant milestone for the company, marking its second gene therapy success and including a valuable Priority Review Voucher, leading to a substantial after-hours stock jump.

Ultragenyx Pharmaceutical (RARE) experienced a significant stock surge following the FDA's full approval of FAYUVI, a groundbreaking gene therapy for Sanfilippo syndrome Type A. This approval is a major corporate catalyst, as FAYUVI is the first-ever treatment for this ultra-rare and fatal childhood disease, opening up a new market for Ultragenyx. The inclusion of a Priority Review Voucher further enhances the value, as these can be sold for hundreds of millions of dollars or used to expedite future drug reviews. This event is a strong positive for RARE, demonstrating successful R&D and regulatory navigation, and could lead to substantial revenue generation and improved investor confidence in the short and long term, despite the stock's previous 12-month decline.

$RARE positive FDA approval of key drug
Source: benzinga
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