US stocks-Wall St slides as AI rally worries deepen

Chinese AI startup Moonshot unveiled Kimi K3, a 2.8 trillion-parameter model it said was the world's largest open-weight AI, adding to investors’ concerns over whether hefty spending by heavyweights will deliver tangible results.

Chinese open-source models have raised some competitive fears, said Angelo Kourkafas, senior global investment strategist at Edward Jones Investments.

"Supposedly, there are some offerings rivaling the performance of Anthropic and OpenAI... potentially that is contributing today to some of that weakness that started in Asia."

Shares of Netflix tumbled 9%, after the streaming giant forecast third-quarter numbers below Street estimates on Thursday, weighing heavily on the communication services sector that slid 2.4%.

Among other movers, Intuitive Surgical shares slid nearly 12.5% after the medical device maker kept its da Vinci procedure-growth forecast unchanged and warned insurance-plan changes may be delaying patient care.