Novartis's U.S. shares fell after the Swiss drugmaker reported results of two late-stage studies of its multiple sclerosis pill that showed a reduction in flare-ups below that achieved by a rival drug from Roche Holding.

American depositary receipts in Novartis fell as much as 4.5% in U.S. midday trading Friday before recovering somewhat, reducing their year-to-date gains.

Novartis said its drug, known as remibrutinib and marketed as Rhapsido for skin condition chronic spontaneous urticaria, met the primary goals of the studies by reducing relapse rates relative to Sanofi's rival treatment Aubagio in patients with relapsing MS, the most common form of the disease. The results were presented at scientific congress MSToronto2026 in Toronto and published in medical journal the Lancet.

The studies showed the drug achieved reductions in the annualized relapse rate of 35.2% and 31.2% compared to Aubagio, the company said. This translated into one relapse every 13 years, it added.

No liver safety signal was observed, Novartis said.

Novartis, which was recently hit by trial failures of cholesterol and neuromuscular drugs, already reported initial findings from the studies last month, but analysts said a look at the full data was required to assess how its drug performed against the competitor product from Roche.

Roche, Novartis's Swiss cross-town rival, previously said its own multiple sclerosis pill, fenebrutinib, lowered the annualized relapse rate by 51.1% and 58.5% in two late-stage studies, but its drug showed signs of potential liver injury.

Analysts at UBS had said before Novartis released the full study data that the company would likely need to deliver efficacy data at least on par with Roche's fenebrutinib with a clean safety profile to trigger a positive market reaction.

Novartis said there were no cases that would raise concerns about drug-induced liver injury in its trials. Roche reported a case of potential liver damage.

By combining high efficacy with a favorable safety profile, the medicine has the potential to support long-term disease management, Novartis Chief Medical Officer Shreeram Aradhye said.