Biotechnology stocks slumped Friday, led by high-flying vaccine makers and drug developers.

Moderna was falling particularly hard. That is nothing new for the stock, which has risen more than sevenfold this year, fueled by a cancer vaccine trial readout in August that launched shares into the stratosphere.

Since then, shares have been volatile. Moderna fell 9.3% to $214.60 on Friday to become one of the worst-performing stocks in the S&P 500.

Novavax fared even worse, plunging 12%. Broad selling pressure across vaccine stocks hit the company hard, amplified by a bearish note from Citi analyst Geoff Meacham late Thursday. Reiterating his Sell rating on the shares, Meacham noted that "timing, economics, and long-term revenue visibility remain difficult to underwrite."

Beyond vaccine stocks, biotech more broadly was falling. The iShares Biotechnology exchange-traded fund, which counts Amgen and Moderna among its largest holdings, was down 1.8% on Friday. Another major holding, cancer-drug developer Revolution Medicines, fell 5.9%.

One down session doesn't necessarily signal the end of the rally. While several biotech high-flyers have enjoyed a banner year -- with Novavax up 67%, Revolution Medicines up 124%, and Moderna up an eye-watering 622% -- a single day in the red doesn't necessarily mean the gains are over.

Several closely watched companies face near-term catalysts in the coming weeks. Moderna, for instance, is slated to present three abstracts on intismeran autogene -- its personalized cancer vaccine co-developed with Merck -- at an oncology conference later this month.

The presentations include expanded results from the Phase 3 trial previewed in August, which assessed a combination of intismeran autogene and Merck's Keytruda as an adjuvant treatment for resected melanoma. Goldman Sachs analyst Salveen Richter characterized these results as "the initial unlock for Moderna's cancer vertical," noting that they marked the company's first positive pivotal data outside its respiratory vaccine franchise.

Indeed, the data appear to have fundamentally reframed Moderna's identity, showing its pipeline extends far beyond Covid-19 and demonstrating the versatility of its core mRNA platform.

Speaking at the 2026 STAT Summit on Thursday, Moderna President Stephen Hoge recalled that intismeran faced deep skepticism early on. "We believed in it, but going into it, you'd have to describe it as a risky bet," Hoge said. "It was a long shot by any stretch of the imagination in the early days."

Revolution Medicines, too, may still have room to run following an impressive rally this year. Shares had a surprisingly muted reaction to the U.S. approval of Rasonque, despite months of buildup surrounding the pancreatic cancer therapy, which drew a minute-long standing ovation at a medical conference ahead of its authorization.

However, a major second market could soon open up. On Thursday, a European Medicines Agency committee recommended granting Rasonque marketing authorization in the European Union, a critical step toward bringing a new option to patients with a notoriously hard-to-treat disease.

With the European Commission facing a 67-day deadline to issue a final verdict, investors now have a clear timeline for the drug's next catalyst. A similar countdown is underway for Eli Lilly, which awaits a decision on marketing authorization for its weight-loss pill, Foundayo.

The road ahead may be tougher for companies like Novavax, which have more to prove, for many other biotechs, a single red day is far from the end of the story.