Moderna Shares Plunge 25% After Possible Leak of Cancer Vaccine Data

Moderna shares fell 25% after what Forbes described as a possible leak of cancer vaccine data, a sharp reversal of a major rally the stock had seen in 2026 on optimism about its personalized vaccine. Karen Knudsen, CEO of the Parker Institute for Cancer Immunotherapy, described the results behind the drop as "extremely encouraging."

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• Forbes described the event as a possible leak of cancer vaccine data that caused the stock to drop 25%.

  «Moderna Stock Plunges 25% After Possible Cancer Vaccine Data Leak»

  Forbes
• The decline marks a sharp reversal of a major rally in Moderna's stock in 2026, driven by optimism about its personalized cancer vaccine.

  «The drop is a sharp reversal of a massive 2026 stock rally fueled by optimism over its personalized cancer vaccine.»

  Forbes
• Karen Knudsen, CEO of the Parker Institute, a nonprofit organization, described the results that triggered the decline as encouraging.

  «are “really encouraging,” says Karen Knudsen, CEO of the Parker Institute for Cancer Immunotherapy»

  Scientific American

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