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Ultragenyx (RARE) stock craters 44% after Angelman syndrome drug fails Phase 3 trial. Ultragenyx shares sink 44% after its Phase 3 Aspire trial for Angelman syndrome treatment GTX - 102 fails to meet its primary endpoint, forcing the company to cut costs. Ultragenyx Pharmaceutical (NASDAQ: RARE) shares are plummeting 44% in Tuesday's session after the company reported that its late - stage drug trial for Angelman syndrome failed to meet its primary goal. What happened. The biotech company announced Phase 3 Aspire trial results on September 2, 2026, revealing that its experimental therapy GTX - 102 did not achieve the primary endpoint of statistically significant improvement in clinical symptoms compared to placebo in patients with Angelman syndrome. The news sent shares into freefall. RARE opened at $14.00 and recently traded around $14.74, down roughly 44% from the previous close of $26.55. Trading volume has surged to approximately 9.3 million shares, well above the stock's average daily volume of about 2 million shares. Company response. Following the failed trial, Ultragenyx said it would cut costs to preserve cash, according to Benzinga. The company did not immediately disclose specific restructuring details. Ultragenyx CEO Emil D. Kakkis did not offer a timeline for when investors might expect an update on the company's strategic plans or pipeline priorities. Why it matters. Angelman syndrome is a rare genetic neurological disorder that affects roughly 1 in 15,000 people in the United States. There is no cure. Success in this indication would have represented a meaningful expansion of the company's rare - disease portfolio beyond its existing approved therapies. The failed trial marks a significant setback for a company that had been making progress elsewhere. In August 2026, the FDA approved GENGLYCOS, Ultragenyx's first gene therapy, for glycogen storage disease type Ia. The company also reported stronger second - quarter earnings, with revenues jumping year over year. Prior to the trial failure, some analysts had viewed the stock as undervalued ahead of key regulatory decisions. Assenagon Asset Management recently sold a large stake in the company, though that sale predates the latest news. Market impact. The sharp decline brings Ultragenyx's market capitalization down to approximately $1.45 billion. Short interest sits at roughly 15.9 million shares, with days to cover near 7.8 based on recent data. Wall Street analysts had not universally abandoned the stock following the news. Some pointed to the company's existing commercial products, including Crysvita and Evkeeza, as potential anchors. However, the market's immediate reaction reflects concern about the company's growth trajectory without a successful neurology program. What comes next. Ultragenyx has not announced plans for the GTX - 102 program or whether it will pursue further development in Angelman syndrome. Investors will likely look for updates on the company's cost - reduction timeline and how it plans to allocate resources across its remaining pipeline. The broader biotech sector has seen volatility in 2026 as the Federal Reserve adjusts interest rate expectations, which can weigh on growth - focused companies with limited near - term profitability. Ultragenyx Pharmaceutical develops treatments for rare and ultra - rare genetic diseases. Its approved products include Crysvita, Mepsevii, Dojolvi, and Evkeeza.

Ultragenyx has published 96-week data from its Phase 3 trial of GENGLYCOS gene therapy for glycogen storage disease type Ia in The Journal of Inherited Metabolic Disease. The therapy, recently approved by the FDA for patients aged eight and older, showed participants achieved a mean 61% reduction in daily cornstarch intake whilst maintaining glycemic control. At week 48, 83% of treated participants met or exceeded their expectations for cornstarch reduction. One-third of the treatment group and 42% of the crossover group completely eliminated nighttime cornstarch dosing. Most participants achieved at least 50% reduction overall. The therapy addresses the disease's underlying cause by enabling the liver to regulate glucose production independently, potentially reducing risks of severe hypoglycaemia from missed cornstarch doses.

Ultragenyx (RARE) has a new gene-therapy launch catalyst, but the 2027 profitability path still has to prove out. What the latest reported quarter says about the current operating story and the main business drivers. Ultragenyx Pharmaceutical Inc. (NASDAQ: RARE) reported second-quarter 2026 revenue of $214 million, up from $167 million in the same quarter of 2025, marking the highest quarterly revenue in the company's history and keeping management's full-year 2026 revenue guidance of $730 million to $760 million intact (Ultragenyx second-quarter 2026 financial results, August 4, 2026). The core business remains concentrated in a handful of commercial rare-disease products. Crysvita contributed $156 million in the quarter, Dojolvi added $27 million, Evkeeza contributed $21 million, and Mepsevii generated $10 million. Discover more Economic news briefing Financial data feed That mix says the current operating story is still driven by execution in the existing commercial portfolio rather than by a single binary pipeline event. Crysvita remains the main engine, and the quarter's revenue strength suggests the base business is holding up well enough to support management's claim that Ultragenyx is on track toward profitability in 2027. At the same time, the company is leaning heavily on a catalyst-rich second half of 2026. In the August 4 release, chief executive Emil Kakkis said Ultragenyx was ready to launch two gene therapy products and preparing for a pivotal Phase 3 GTX-102 data readout in Angelman syndrome. That setup became more tangible on August 19, when Ultragenyx announced U.S. FDA accelerated approval for GENGLYCOS, also known as DTX401, for adults and children aged eight and older with glycogen storage disease type Ia (Ultragenyx GENGLYCOS approval release, August 19, 2026). The approval matters because it gives the company its first gene-therapy approval and adds a potentially meaningful growth leg to a commercial base that is already scaling. It also changes the investor discussion from "can Ultragenyx launch a gene therapy?" to "how much operating leverage can that launch create?" What the latest reported revenue mix, margins, balance-sheet context, and management commentary imply for investors now. The quarter was strong on revenue but still loss-making, which is why the balance-sheet and expense profile remain central to the investment case. Total operating expenses were $289 million in Q2 2026, versus $275 million a year earlier. Net loss improved to $92 million, or $0.90 per diluted share, from $115 million, or $1.17 per diluted share, in Q2 2025 (Ultragenyx second-quarter 2026 financial results, August 4, 2026). In other words, Ultragenyx is getting better scale from its revenue base, but it is not yet close enough to profitability for investors to ignore execution risk. Discover more Market trend forecasts Business news updates Stock performance tracking Cash, cash equivalents, and marketable securities stood at $436 million as of June 30, 2026, while net cash used in operations was $97 million in the quarter. That is enough liquidity to keep funding launches and development, but it is not an idle surplus. The company still needs product revenue growth and tighter cost discipline to keep the 2027 profitability target credible. Management reiterated that combined R&D and SG&A expense should be flat to down low-single digits in 2026 versus 2025 and decline by at least 15% in 2027 versus 2025. For investors, that means the margin story depends on both commercial execution and spending discipline landing at the same time. GENGLYCOS adds an important strategic layer to that equation. The approval release described GSDIa as affecting 1,500 to 2,500 patients in the United States and 6,000 to 8,000 patients across commercially accessible geographies. Ultragenyx also said it received a Priority Review Voucher with the approval, will support access through its UltraCare program, and will distribute the therapy through a national network of qualified treatment centers. Just as important, the company said GENGLYCOS is manufactured entirely at its Bedford, Massachusetts gene-therapy facility, which suggests management believes the manufacturing and launch infrastructure is ready for commercial use rather than purely clinical supply. What investors should watch next. The first thing to watch is whether GENGLYCOS becomes more than a symbolic approval. Accelerated approval is valuable, but investors now need to see evidence that access, treatment-center activation, and patient onboarding can convert approval into a commercial contribution without creating a new cost overhang. The company has already framed support infrastructure and manufacturing readiness as launch strengths. The next proof point is operational execution. Discover more Earnings call transcripts Real-time stock quotes The second watch item is whether the broader late-2026 catalyst slate supports the profitability path instead of distracting from it. On August 4, Ultragenyx highlighted a September 19, 2026 PDUFA date for UX111 and a September-or-October 2026 data window for the Phase 3 Aspire study of GTX-102. Positive outcomes could strengthen the company's multi-product growth outlook. Weak outcomes would leave more of the 2027 profitability burden resting on the existing commercial portfolio plus GENGLYCOS. Finally, investors should keep an eye on how much of the Q2 revenue momentum is durable. A quarter with $214 million in revenue and a narrower net loss is a solid base, but not yet a self-funding model. Ultragenyx has moved from a story dominated by pipeline promise to one that must increasingly show financial conversion. If management can pair new-launch execution with the expense discipline it has promised, the stock's post-approval optimism can hold. If not, the market may start treating the approval as an important scientific milestone that still leaves the operating model unfinished. Key signals for investors. * Q2 2026 revenue hit a company record at $214 million, led by Crysvita at $156 million, showing that the base commercial portfolio is still scaling. * Net loss improved to $92 million from $115 million a year earlier, but Ultragenyx remains dependent on continued growth and cost control to reach its 2027 profitability target. * The $436 million cash balance gives the company room to launch GENGLYCOS and keep advancing late-stage programs, but the quarterly cash burn still matters. * GENGLYCOS approval adds a real commercial catalyst because Ultragenyx says it has treatment-center access support and in-house manufacturing already in place. * The next major test is whether late-2026 catalysts, especially UX111 and GTX-102, reinforce the path to profitability rather than raise fresh execution questions.