Amazon just opened Project Rainier, one of the world’s largest AI compute clusters, in partnership with Anthropic. Amazon’s third-quarter profits rose 38% to $21.2 billion, but a big part of the jump had nothing to do with its core businesses of selling goods or cloud services. The company reported a $9.5 billion pre-tax gain from its investment in the AI startup Anthropic, which was included in Amazon’s non-operating income for the quarter. The windfall wasn’t the result of a sale or cash trans...