An analyst note flagging a possible slowdown by Microsoft in leasing for data center capacity grabbed the market's attention on Monday, lending credence to skepticism among investors worried that the AI-led stock-market boom might be overdone.

A research note written by TD Cowen analysts says Microsoft has cancelled leases in the U.S. with at least two private data-center operators totaling a couple hundreds of megawatts and also is not converting so-called statements of qualifications into leases.