Moderna (NASDAQ: MRNA ) stock experienced a brutal 24 hours of trading, dropping 17.57% from $245.81 to $202.63 on October 22, and extending the losses by another 4.40%, falling to $193.71 by press time in the Friday pre-market.
Moderna stock price one-day chart. Source: Google
The sudden MRNA share price downturn appears to have been driven by two key factors. First, the early results for the company’s Phase 3 study for its personalized cancer – melanoma primarily – vaccine briefly leaked.
Second, several notable Wall Street firms revised their price targets and ratings of Moderna stock, with Citi’s (NYSE: C ) ‘Sell’ recommendation and $80 forecast arguably being the most impactful.
Specifically, along with estimating that MRNA shares will plunge 60.52% in the next 12 months, analyst Geoff Meacham explicitly described the company’s recent ascendance and valuation as ‘unjustifiable’.
Indeed, between the two, the fact that the supposed leaked results proved generally positive failed to prevent investors from reconsidering whether Moderna merits its $80.89 billion market capitalization.
Moderna stock price performance
Zooming out highlights the sheer scale of MRNA stock’s rise in 2026. Driven by earlier vaccine announcements, Moderna shares entered a powerful uptrend in late August that, on the eve of the latest plunge, left them 696.53% in the green year-to-date (YTD).
Furthermore, the previous upsurge was large enough that even the 21% 24-hour collapse left the equity up 556.61% YTD.
Moderna stock price YTD chart. Source: Google
Moderna vaccine ally stock drops on Moderna equity crash
Lastly, the stock of Merck (NYSE: MRK ), the company cooperating with Moderna on the vaccine, saw directionally similar moves to MRNA, though of a far smaller magnitude.
Specifically, MRK shares declined 1.76% in the Thursday session and extended the losses by another 0.53% in the Friday, October 23, pre-market, falling from $147.24 at the latest close to $146.46 at press time.
Merck stock price one-day chart. Source: Google
Similar to Moderna, the most recent drop had a comparatively small impact on the YTD performance, and Merck stock remains 38.32% in the green in 2026.
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