Moderna Soars 177% on Cancer Vaccine Win; Merck Adds $44B
Wednesday's session (August 19) had one dominant story, and it was in health care: Moderna soared 176.97% to $174.38, its largest single-day gain on record, lifting its market value from roughly $25B to $69B. The trigger was INTerpath-001, the Phase 3 trial of intismeran autogene — the individualized mRNA cancer vaccine Moderna developed with Merck — combined with Keytruda. In 1,137 patients with high-risk stage IIB–IV melanoma whose tumors had been surgically removed, the combination hit its primary endpoints, showing statistically significant improvements in both recurrence-free survival and distant metastasis-free survival versus Keytruda alone.
The mechanism ran through the valuation. Moderna had been priced off a post-Covid revenue line that was still shrinking; the Phase 3 readout turned individualized neoantigen therapy into a commercializable product candidate for the first time and made the same platform's trials in other tumor types worth pricing in. Merck gained 12.6% — about $44B in market value on its own. BioNTech rose 22%, Novavax 10.8% and Pfizer 3.6%; the Nasdaq Biotechnology Index added 6.4% and the health care sector's 3.5% gain was its best day since April 2025.
