These Were the 2 Worst-Performing Stocks in the Dow Jones Industrial Average in May 2025

The Dow Jones Industrial Average (DJINDICES: ^DJI) index edged 3.9% higher in May, with 70% of its 30 constituent stocks ending the month in positive territory. However, the two worst-performing Dow stocks in May -- both from the healthcare sector -- kept the index's rally in check, with one of them plunging over 25%.

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1. UnitedHealth Group

Shares of UnitedHealth Group (NYSE: UNH) crashed 26.6% in May after multiple negative developments sent shockwaves through the investing community. In mid-May, UnitedHealth suddenly replaced its CEO, Andrew Witty, with former CEO Stephen J. Hemsley with immediate effect and suspended its earnings outlook for the full year because of a surge in medical costs.

In between, The Wall Street Journal reported a criminal investigation against UnitedHealth by the Department of Justice for a "possible medicare fraud." Days later, The Guardian released a scathing report alleging UnitedHealth put patients' health at risk by paying secret bonuses to nursing homes to cut hospital transfers.

For now, UnitedHealth expects to "return to growth" in 2026 and has sued The Guardian for defamation. Regaining investor confidence, however, may not be easy. The stock is down 38% so far this year, as of this writing.

2. Merck

Merck (NYSE: MRK) stock lost 9.8% in May and plunged to its 52-week low of $73.31 a share after President Donald Trump signed an executive order directing drugmakers in the U.S. to cut the prices of prescription drugs. This comes at a time when Merck already expects tariffs to add $200 million to its costs this year.

Investors are also worried about Merck's future once its blockbuster oncology drug Keytruda loses patent exclusivity. In mid-May, analysts at Citi slashed Merck stock's price target to $84 per share from $115 per share citing the pharmaceutical company's growth challenges and a "lack of urgency" to develop a business that could soften the impact of a potential loss of up to 20% of sales for Keytruda once its patent expires.

Merck, however, has a strong pipeline, remains committed to dividend growth, and yields 3.9%.

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Citigroup is an advertising partner of Motley Fool Money. Neha Chamaria has no position in any of the stocks mentioned. The Motley Fool has positions in and recommends Merck. The Motley Fool recommends UnitedHealth Group. The Motley Fool has a disclosure policy.