$Moderna(MRNA.US) is now the best performing stock in the S&P 500 this year, up more than 660% in 2026
That puts a COVID vaccine maker ahead of every AI name in the index, including $Sandisk(SNDK.US) at roughly +566% and $Dell Tech(DELL.US) at roughly +370%. The S&P 500 itself is up about 14%The run took off on Aug 19, when $Moderna(MRNA.US) and $Merck(MRK.US) said their personalized mRNA cancer vaccine delayed the return or spread of melanoma in a Phase 3 trial. Back in mid-August the stock was still down close to 90% from its pandemic highLast week added two more catalysts. $Moderna(MRNA.US) rejoined the Nasdaq-100, replacing $Warner Bros. Discovery(WBD.US), and the NYT reported the NIH is planning a public-private push to speed up cancer vaccines. Shares gained 18% on the week and closed at their highest level in more than four yearsFull trial data is due Oct 24, and the companies are preparing for regulatory approval next yearThe S&P 500's top performer is a science bet, not an AI trade. Most of this move is priced on data nobody outside $Moderna(MRNA.US) and $Merck(MRK.US) has seen yet, so Oct 24 is when the market finds out whether this is a real oncology platform or a stock that ran too far ahead of the evidenceSource: StockMarket.News






