Moderna shares surged 176.97% on Aug. 19, 2026, after the company and Merck reported positive Phase 3 data pairing Moderna's intismeran autogene with Merck's KEYTRUDA against melanoma. The stock's market cap rose from $25 billion to $69 billion in a single session, while trading volume swelled far above its recent average.
Melanoma trial data drives the rally
Moderna closed at $174.38, up $111.42 on the day. The move followed positive Phase 3 data from a trial combining Moderna's intismeran autogene with Merck's KEYTRUDA in melanoma patients. It marks Moderna's first individualized neoantigen therapy (INT), and the combination delivered meaningful improvements for patients compared with KEYTRUDA alone. Investors are now watching for the company's FDA plans and further developments for the treatment.
Volume spikes alongside the rally
Trading volume reached 185.1 million shares, about 1,819% above its three-month average of 9.6 million shares. Moderna IPO'd in 2018 and has grown 838% since going public, but today's swing stands apart from that longer run.
Beyond melanoma, intismeran is already in multiple Phase 2 and Phase 3 cancer trials. Therefore, the market is pricing in the potential for growth across other cancer indications should the INT platform keep showing results, not just melanoma alone.
Peers move alongside broader markets
The S&P 500 rose 0.21% to 7,708, and the Nasdaq Composite gained 0.16% to 26,331. Among other mRNA-focused biotechnology names, BioNTech closed at $113.12, up 21.96%, while Pfizer closed at $28.25, up 3.69%.
Source: The Motley Fool
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