If Moderna's CEO Is Right, the Stock's Rally Could Just Be Getting Started

Moderna (NASDAQ:MRNA) has been the hottest stock in the S&P 500 this year, and it hasn't been close. Up around 650%, the next-best-performing stock is Sandisk, with gains of about 380% thus far.

It's been an exceptional performance for Moderna, which struggled in recent years after its sales nosedived as demand for its COVID vaccine and pill dwindled.

Now, however, there's plenty of excitement around the business due to the cancer vaccine it's been working on with Merck. And if it can be as successful as Moderna's CEO believes it can be, then it may not be unrealistic to expect the healthcare stock to surge even higher in value.

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Vaccine drastically improved outcomes for melanoma patients

Moderna and Merck have been working on a cancer vaccine for years, and the results are starting to pay off significantly. A recent late-stage trial demonstrated that the vaccine, intismeran, reduced the risk of death or recurrence in melanoma patients when paired with Keytruda, Merck's highly successful cancer drug, by an impressive 42%.

Investors are thrilled with the results and the money that intismeran may bring in for Moderna in the future. CEO Stéphane Bancel is excited about the possibility for the treatment to also go beyond just melanoma, stating that, "We believe it will work everywhere Keytruda works."

That would be monstrous, as Keytruda brought in $32 billion in revenue for Merck's business last year. A growth catalyst, meanwhile, is exactly what Moderna needs, as in the past three years its revenue has been declining sharply, totaling just $1.9 billion throughout all of 2025.

Moderna's stock may still have plenty of upside, but expectations will be high

If intismeran proves to be the real deal for Moderna, unlocking all sorts of growth for the business, then it may not be hard to see a path for the stock to rise even higher, potentially doubling from where it is right now. Merck, whose business centers heavily around Keytruda, has a market cap of around $370 billion, while Moderna's valuation is far lighter, at less than $90 billion.

There are, however, sky-high expectations for the stock these days, in light of not only the encouraging trial results but also the CEO's comments and excitement. At the end of the day, intismeran isn't approved yet, and while there is potential for it to help with other illnesses, investors shouldn't assume that's a sure thing.

The healthcare company has a ton of potential, but massive gains at this stage are by no means a guarantee, especially given the company's underwhelming financial results. Investors should tread carefully.

David Jagielski, CPA has no position in any of the stocks mentioned. The Motley Fool has positions in and recommends Merck and Moderna. The Motley Fool has a disclosure policy.