Moderna Tumbles 10% and Novavax Drops 12% as Profit Taking Hits Vaccine Stocks Ahead of Cancer Data

Vaccine stocks came under heavy selling pressure on Friday, with profit taking landing hardest on the names that had run the furthest. Moderna fell 10% to $214 and Novavax slid 12% to $11.23 in afternoon trading, while BioNTech eased modestly and Pfizer held relatively steady.

Moderna's retreat follows an extraordinary 663% gain in 2026, fueled by its cancer vaccine program developed with Merck. The company and Merck announced in August that their experimental melanoma vaccine passed a final-stage trial, sending the stock up 177% in a single session. Full trial data is expected on October 24, and analysts noted that uncertainty ahead of that release, combined with stretched valuations, is drawing sellers despite the strong underlying catalyst.

Novavax, the smallest name in the group, took the steepest percentage loss as the vaccine sector selloff concentrated pressure on the most thinly traded shares. The decline reflects a broader pattern of rotation out of the sector after a prolonged rally, rather than any company-specific negative development. Pfizer, which has a more diversified revenue base, was largely insulated from the move.