Moderna pulls back after massive gains on cancer vaccine trial results
MRNA•Shares fall after sharp rally on trial results
Shares of Moderna MRNA.O tumble 20.5% to $139.30, while Merck MRK.N falls 1.9% at $149.35.
The pullback follows a blistering rally a day earlier that more than doubled Moderna's stock, adding more than $44 billion in market value.
The companies said on Wednesday a personalized mRNA cancer vaccine together with Merck's immunotherapy Keytruda reduced the risk of recurrence and spread of melanoma in a late-stage trial.
MRNA is set for its biggest one-day percentage drop in more than two years, if losses hold. The slump is on track to erase about $14.3 billion in market value at the current level.
Analysts say expectations may have become too high
"While we were thrilled to see a positive market reaction for the definitive success of the therapeutic cancer vaccine, intismeran autogene, the reception was overly optimistic and creates expectations that we believe will be difficult to meet," Leerink Partners analysts said.
MRNA shares are still up more than 500% from their 52-week low of $22.28 hit in November 2025.
Including session's move, MRNA's stock has gained 368%, and MRK is up 42% year to date.
