What happened to Novartis stock on September 8, 2026?
Novartis shares fell close to 10% on September 8, 2026, after the drugmaker said its del-desiran therapy for myotonic dystrophy type 1 missed the main goal of its Phase 3 HARBOR study. Investing.com reported the Zurich-listed shares down 10.3% to CHF 112.60, and CNBC called it the stock's worst trading day on record.
What is del-desiran and why did its trial fail?
Del-desiran, also known as delpacibart etedesiran, is designed to clear the toxic RNA that causes muscle weakness in myotonic dystrophy type 1 (DM1), a disease with no approved treatments. The 150-patient, 54-week HARBOR study did not show a statistically significant improvement over placebo on its main measure, hand-opening speed, though Novartis said secondary and exploratory data showed some clinical activity.
Why did Dyne Therapeutics and Sarepta fall too?
Neither company reported new data of its own. Dyne Therapeutics dropped 31% in premarket trading to $16.76 from a $24.28 close, because its z-basivarsen candidate targets the same toxic DMPK RNA in DM1 that del-desiran failed to clear. Sarepta fell as much as 7.6% to $20.80, since its SRP-1003 candidate targets the same RNA through a different delivery ligand. The market treated one company's miss as a signal for the whole approach.
Is this Novartis's first trial setback this week?
No, it is the third in eight days. On September 4, pelacarsen failed to reduce cardiovascular events in the Lp(a)HORIZON trial despite lowering Lp(a) levels, and on August 24 Novartis paused eight trials of its rap-cel cell therapy after three patients died from a severe immune reaction called IEC-HS.
How did the pelacarsen failure hit other drugmakers?
Ionis Pharmaceuticals, which partnered with Novartis on pelacarsen, is still down roughly 10% since the September 4 announcement, and Amgen fell about 5% on the same news even though its own Lp(a) drug works differently. Amgen's olpasiran and Eli Lilly's lepodisiran remain in active Phase 3 trials, enrolling roughly 7,000 patients in Amgen's OCEAN(a) outcomes trial and 12,500 in Lilly's ACCLAIM-Lp(a) study. Neither has reported results yet.
Is Novartis walking away from these drug programs?
Not yet. Novartis said it is still reviewing the full HARBOR dataset and will talk to regulators about next steps for del-desiran, a drug whose peak sales potential Novartis had put above $5 billion when it acquired the asset through Avidity Biosciences. Jefferies analyst Michael Leuchten kept a Hold rating on the stock, warning that Novartis's growth targets now look harder to hit without more acquisitions. Novartis itself kept its 5-6% sales growth guidance through 2030 unchanged.
What should traders watch next?
Whether Amgen and Lilly's Lp(a) trials succeed where pelacarsen failed will decide if today's selloff was specific to Novartis's chemistry or a warning for the entire Lp(a) drug class. On the DM1 side, Sarepta and Dyne still have their own separate data to report, and neither has confirmed any change to its own trial timeline because of Novartis's readout.
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