Plug Power shares fell approximately 10% on Monday, May 18, 2026. The decline continues a broader correction in the fuel cell sector as investors unwind previous premiums. Market participants engaged in profit-taking following a rally earlier in the week.
A U.S. sovereign credit rating downgrade by Moody's triggered a wider risk-off environment. This shift specifically impacted high-beta and loss-making clean energy companies.
The sell-off follows a positive reaction to Plug Power’s Q1 2026 earnings reported on May 11. The company previously reported significant revenue growth and improved margins.