Nebius and CoreWeave shares slide after Ken Griffin warns of AI bubble

Shares of Nebius and CoreWeave have fallen sharply this month, with CoreWeave down over 60% from its peak, as billionaire investor Ken Griffin warned the market is "clearly in an AI bubble," erasing billions in value. Griffin, founder of Citadel and Citadel Securities, joins other prominent figures like Ray Dalio and Michael Burry in flagging risks. Burry has taken short positions in Nebius. The AI Stock Bubble Index has risen to 74, indicating elevated risk, while research firm Gartner warns AI infrastructure firms may need trillions in revenue to justify spending or face major impairments by 2030. Despite strong revenue growth—CoreWeave reported over $2.5 billion in Q3 and Nebius over $529 million—both companies face risks from rising competition, including new entrants like Nscale and Lambda, and potential write-downs as newer chips arrive. High short interest persists amid these concerns.