Moderna's +177% day — and it is still 64% below the 2021 peak

Moderna closed at $174.38 on August 19, up 177.0% from the prior close of $62.96, on 192 million shares — 29 times its trailing three-month average volume. The move followed the announcement that the Moderna–Merck personalized mRNA melanoma vaccine met its goals in a late-stage trial with Keytruda, the first successful phase-3 readout for an mRNA cancer vaccine. It is by far the largest one-day gain in the stock’s history; the prior best was +27.8% in February 2020. At the post-move market value, the session added roughly $43 billion.

The chart is the honest frame: the stock began 2026 at $30.86, so it is up 465% year to date — and still 64% below its August 2021 peak of $484.47. A one-day repricing of this size reflects a binary event resolving rather than a trend, and it says nothing about where the stock goes from here.