COVID Vaccine Maker Moderna Is S&P 500's Best Stock of 2026, Up 663%

Artificial-intelligence enthusiasm has powered the market in 2026, yet the S&P 500's top performer year-to-date is no chipmaker. That distinction belongs to a COVID vaccine maker, whose stock closed Friday at $225, up 663% this year.

The top spot is tied to a cancer vaccine trial whose complete findings have not been published. Back in mid-August, Moderna shares were still nearly 90% below their pandemic-era peak.

Moderna's Path Past the AI Leaders

The company in question is Moderna (MRNA), most famous for its COVID vaccine. Moderna and drugmaker Merck said on August 19 that their experimental cancer vaccine had passed a final-stage trial in patients with skin cancer.

The announcement came after a difficult period. Sales of the COVID vaccine had collapsed, and Moderna eliminated more than 800 jobs last year.

The Inquirer said shares closed 177% higher that day and fell 24% the next. BeInCrypto had already highlighted Moderna's 2026 comeback in June, when the stock was up 125% after a flu vaccine approval.

On Friday, the advance continued, and Moderna rejoined the Nasdaq-100, the index of Nasdaq's biggest non-financial companies.

BREAKING: $MRNA is up +8% today as it joins the Nasdaq-100, and it is now the best performing S&P 500 stock of 2026, up +620%.

$10,000 invested in Moderna at the start of 2026 is now worth over $72,000.

— Bull Theory (@BullTheoryio), October 9, 2026

Nasdaq said the index is tracked by more than 200 funds holding over $800 billion, so they had to buy the stock.

Also on that day, The New York Times reported a national cancer vaccine push modelled on the COVID effort, expected to launch in December. Moderna ended the session 14% higher.

AI-related stocks are not far off the pace. SanDisk, which sells memory chips to AI data centers, has climbed 566% this year, lifted by demand for AI memory chips. The S&P 500 index is higher by roughly 14%.

October Holds the Key for Moderna Stock

So far, Moderna and Merck have only said the vaccine worked, without saying how well. Investors will receive the complete results on October 24 at a major cancer conference in Madrid.

Marco Gerlinger, a professor at Barts Cancer Institute, told the Pharmaceutical Journal: “It provides proof of principle that personalised cancer vaccines work.”

Not everyone is buying into the rally, though. Martin Shkreli, a former drug company executive, thinks the Moderna stock bubble has at most six months before it bursts.

moderna $MRNA is a great short if you can tough it out and wait 6 months

— Martin Shkreli (@MartinShkreli), October 9, 2026

Moderna's market value now stands at about $89.8 billion, and competitors BioNTech and Genentech are testing a cancer vaccine of their own.