Moderna and Merck shares slump after melanoma vaccine data leaks
Moderna and Merck shares fell after data on their personalized melanoma vaccine disappointed Wall Street. Moderna dropped as much as 26% on Thursday, a record intraday decline, while Merck slipped 3.9%. The data leaked ahead of schedule and were later confirmed by Merck: the vaccine reduced the risk of cancer recurrence by 42% and the risk of metastasis by 38%. The results were due to be presented on Saturday at the European Society for Medical Oncology meeting in Madrid.
In 40 seconds
- Moderna fell as much as 26% intraday, a record, and Merck slipped 3.9% after the data emerged.
- The vaccine reduced the risk of cancer recurrence by 42% and the risk of distant spread by 38%.
- The data leaked on social media platform X ahead of schedule and Merck later confirmed them.
IASummary generated by artificial intelligence from a story by EL PAÍS. It may contain errors: the original source prevails.




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