A selloff in chipmakers dragged down stocks after leaders of artificial-intelligence giants proposed slowing the technology’s development, with a rally in oil also weighing on sentiment.

Chip stocks slided in morning trading. Direxion Daily Semiconductors Bull 3x Shares fell 18%; Marvell Technology fell 9%; Intel fell 8%; Micron, SanDisk, and SK hynix fell 7%; AMD and Western Digital fell 6%; Seagate fell 5%; Broadcom and Nvidia fell 4%.

Optical communications stocks dropped in morning trading. Corning and Coherent(COHR)$ fell 10%; AXT, Semtech, and Lumentum fell 9%; Credo Technology and Applied Optoelectronics fell 8%; Ciena fell 7%.

A 3,800-word missive by Anthropic PBC Chief Executive Officer Dario Amodei — which was endorsed by Anthropic PBC CEO Sam Altman and SpaceXAI CEO Elon Musk — said development of the most-advanced systems must be slowed in order to prevent AI slipping beyond human control and inflicting catastrophic harm.

On Monday, Microsoft’s AI researchers have released a new set of guiding tenets that they say boil down to five words: People matter more than AI.

If the latest developments push out the timing of promised AI returns, it makes sense that investors would become less enthusiastic, according to Matt Maley at Miller Tabak.