Moderna and Merck shares tumble after unverified vaccine details surface on X

Moderna and Merck experienced a rapid decline in their stock prices after unverified information about a personalized vaccine for a severe form of skin cancer appeared on X. The leaked content mentioned the vaccine name intismeran autogene and claimed a 42% drop in recurrence or mortality, based on a report circulated on the platform. Previous studies indicated a 49% figure, though those results were not comparable to the new data.

Prior to the incident, Moderna's shares had climbed over 500% for the year and Merck's were up nearly 40%, reflecting strong market optimism after the August announcement of the vaccine. The unexpected drop highlights the sensitivity of biotech valuations to rumors and the importance of verified data. Investors and observers are watching how the situation will affect the companies' future development and market confidence.