Moderna shares plunge 25% on unverified melanoma vaccine data leak

Moderna's stock fell 25% after unverified data on its mRNA melanoma vaccine (developed with Merck) leaked on X, while Merck fell only 3%. The data's authenticity and clinical implications are unconfirmed, creating uncertainty around the vaccine's efficacy and regulatory path. The market reaction reflects heightened sensitivity to oncology pipeline news, but the lack of verification suggests potential overreaction.

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