Vaccination rates are declining, and former "star vaccine stock" Moderna has become the most shorted U.S. stock.

Vaccine manufacturer Moderna has become the most shorted company in the S&P 500 index, with its stock price falling to pre-pandemic levels. As vaccination rates in the US continue to decline, this former star company is facing unprecedented challenges.

According to media reports on Monday, short-selling data firm S3 Partners noted that since the end of September, Moderna has been the most shorted stock in the S&P 500. In 2025, short sellers have gained approximately $622 million in unrealized profits from the company's stock. Moderna’s shares closed at $23.72 on Friday, down 43% so far this year, returning to levels last seen in February 2020.

This company, which turned CEO Stéphane Bancel into a billionaire during the pandemic, is now facing plunging revenue and ongoing losses.

According to a November 21 report from investment bank Jefferies, compared to the same period last year, the number of Americans receiving COVID vaccines has dropped by about 24%. Under the influence of US Health Secretary Robert F Kennedy Jr's months of anti-vaccine rhetoric, market demand for vaccines has shrunk sharply. Despite adequate supply, analysts point out that "vaccine fatigue" is keeping vaccination rates consistently below 2023 and 2024 levels.

Sharp Decline from Peak to Trough

When Moderna joined the S&P 500 index in July 2021, it was at its peak. That year, the US government purchased hundreds of millions of doses of Moderna's COVID vaccine, CEO Stéphane Bancel became a billionaire, and the company's operating profit margin once exceeded that of Warren Buffett's Berkshire Hathaway.

But since 2023, Moderna has been operating at a loss, which began before Kennedy brought vaccine skepticism to Washington this year. Compared to 2021, the company’s revenue has dropped by more than 80%. This trend reflects a structural change in vaccine market demand rather than simply policy factors.

William Blair analyst Myles Minter said that due to excessive reliance on the vaccine business, Moderna has limited appeal to large pharmaceutical companies. He pointed out, "You need to see some quite convincing oncology data" to interest potential acquirers.

Double Pressure from Policy and Supply

As a longtime vaccine skeptic, Kennedy's policies are reshaping the US vaccine market. In June of this year, he dismissed all members of a top vaccine advisory committee, and two months later restricted government recommendations of COVID vaccines. Last week, a US Centers for Disease Control and Prevention website under Kennedy’s department was modified to state: "Research has not yet ruled out the possibility that infant vaccines may cause autism."

Seema Shah, Director of Epidemiology and Immunization in San Diego County, said that the drop in vaccination rates is "not surprising." She pointed out that vaccine shipment delays this year caused pediatric clinics to postpone vaccinations until supplies stabilized. These delays "definitely led to slower growth compared to the past two years."

Faced with policy pressure, Moderna’s lobbying spending in Washington this year has exceeded $1.2 million, a company record.

Seeking a Breakthrough in Transformation

At Thursday’s investor day event, Moderna executives declared the company would turn a corner beginning in 2026. The company is expanding sales outside the US and racing to apply its mRNA technology to cancer treatments.

Moderna Chairman and Flagship Pioneering CEO Noubar Afeyan said in an interview that short-selling of the stock has not changed the company’s actions. He emphasized that people should not forget the harmful impact of COVID, and currently more than 10 million people are suffering from its long-term symptoms.

Moderna said sales from Australia, Canada, and the UK will help the company achieve up to 10% revenue growth next year. In 2027, Pfizer's agreement to supply COVID vaccines to the EU will expire, opening up competition in the European market for Moderna.

The company’s CFO Jamey Mock said, "We see a financial turning point and believe we can achieve break-even by 2028." Ultimately, Moderna hopes its vaccine business can generate enough cash flow to support its cancer research efforts.

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