Moderna Sheds Up to 25% in Profit-Taking Selloff After Historic 177% Cancer Vaccine Surge

Moderna shares fell as much as 25% on Thursday, erasing roughly $18 billion in market value after the stock's record single-day gain of 176.9% on Wednesday. The rally had been driven by positive Phase 3 results from the INTerpath-001 trial of intismeran autogene, an mRNA-based personalized cancer vaccine co-developed with Merck, which met its primary endpoints in patients with completely resected stage IIB-IV melanoma when combined with Merck's Keytruda. By midday Thursday, shares were trading near $142.70, down about 18% to 20%, before extending losses to approximately 24% in afternoon trade, according to multiple market trackers.

Forbes reported Moderna's market capitalization fell from $69.6 billion at Wednesday's close to $51.5 billion. Despite the pullback, Moderna shares remain up roughly 351% year-to-date. The stock led all pre-market volume with approximately 14.2 million shares changing hands in early trade.

Analysts who raised price targets in response to the trial data kept several of those targets below Wednesday's closing price, raising questions about how much of the clinical breakthrough had already been priced in. BioNTech fell around 4% and Merck slipped modestly in sympathy, though a Morgan Stanley analyst maintained that Merck remains a buy. Barron's noted the Wednesday surge had also triggered a short squeeze that spilled into semiconductor names.

A separate disclosure revealed that former President Trump had purchased up to $50,000 of Moderna shares on March 2 and again on March 17, with only a partial sale in May, leaving him holding a position that was up more than 150% as of Wednesday.