WASHINGTON (dpa-AFX) - Moderna, Inc (MRNA) shares suffered their steepest decline since August after leaked late-stage trial results for its personalized melanoma vaccine showed a smaller risk reduction than an earlier study.
The stock fell as much as 26 percent before closing at $202.63, down $43.18, or 17.57 percent, wiping more than $17 billion from Moderna's market value. Partner Merck also fell before recovering part of its losses.
The leaked results reportedly showed Moderna's vaccine, combined with Merck's Keytruda, reduced the risk of cancer recurrence or death by 42 percent. An earlier, smaller trial had shown a 49 percent reduction, although the studies involved different patient populations and are not directly comparable.
Merck confirmed the trial data had been released early. Full results are scheduled to be presented Saturday at a major cancer conference in Madrid.
Moderna shares had nearly quadrupled since mid-August after the company announced that the trial had met its goals.
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