Oct 30 (Reuters) – Market concerns over the cost of the AI boom intensified after U.S. stocks closed on Thursday, as Amazon and Intel earnings showed that the race to build AI infrastructure is not only squeezing tech companies but also starting to weigh on consumers. Amazon shares fell about 7% in after-hours trading, while Intel plunged about 18%. The selloff quickly spread to other companies, with AI cloud service providers CoreWeave, Nebius, and Iren dropping about 6% to 7% in after-hours trading. A broader shift is underway in how large tech companies finance spending, with massive data center investments turning once lightly indebted companies into major borrowers. Alphabet and Meta both posted net cash outflows in the September quarter. Microsoft is the only company in that group not burning cash, but on Thursday it also launched a $25 billion bond offering. Tech giants can still sustain this level of spending, but investors have grown increasingly cautious about smaller AI cloud companies that are borrowing heavily to meet large backlogs of orders.