European chip stocks plunge after AI leaders urge slowdown

European semiconductor stocks suffered their sharpest single-day sell-off in months on Monday after leaders of the world's most prominent artificial intelligence companies called for a slowdown in the development of advanced AI models, triggering a broad reassessment of chip demand tied to the technology.

Soitec led the decline on the Stoxx Europe 600, dropping as much as 12.6% in Paris trading. Infineon shed about 6.3% to roughly €54.86 on Xetra, falling back below its 200-day moving average and erasing the prior session's near-5% rally. Aixtron lost 8.3% to €34.44, with Morningstar noting it was among the steepest decliners on the Stoxx 600. Dutch equipment makers ASML ↘ 7.25% and ASM International fell 4.4% and 5%, respectively, according to Reuters.ad-hoc-news+3

AI Leaders Sound the Alarm

The sell-off was sparked by Anthropic CEO Dario Amodei, who published an essay over the weekend titled "We Must Pace the Frontier," calling for a coordinated global slowdown in frontier AI model development. "We must slow the pace at which we improve the capabilities of AI models," Amodei wrote, warning that AI agent swarms could become capable of "taking over the entire internet" within six to 12 months. OpenAI CEO Sam Altman echoed the sentiment, telling employees his company is open to slowing development, though he expressed concern that competitors might not coordinate, according to Bloomberg as reported by Barron's.axios+1

The New York Times reported that technology stocks fell across Asia, Europe, and the United States as markets digested the warnings. The Philadelphia semiconductor index dropped roughly 5%, while South Korea's Kospi fell more than 3%.nytimes

Collateral Damage Beyond Chips

The fallout extended well beyond chipmakers. Siemens Energy tumbled about 8% to €132.66 as investors questioned the AI-driven electricity demand narrative that had powered the stock's rally. In Spain, companies with data center exposure were hit hard: Solaria fell 8.4%, ACS dropped 6.5%, and Acciona ↘ 2.75% lost 5.7%.democrata+2

XTB analyst Javier Cabrera called the punishment "excessive," though he acknowledged that a real halt in technology investment would hurt companies with data center exposure. Bankinter analysts noted that behind the alarm, AI companies may also have an interest in prompting governments to establish regulations that serve as barriers to entry against smaller competitors.democrata

UBS reiterated a neutral rating on Infineon with a €64 price target, implying the stock trades at a price-to-earnings ratio of about 21 on 2027 estimates. Infineon's next earnings release is scheduled for November 10, offering investors their next window into how the AI demand picture is evolving.ad-hoc-news