A.I. Start-Ups Face a Rough Financial Reality Check

Call it the end of the beginning of the A.I. boom.

Since mid-March, the financial pressure on several signature artificial intelligence start-ups has taken a toll. Inflection AI, which raised $1.5 billion but made almost no money, has folded its original business. Stability AI has laid off employees and parted ways with its chief executive. And Anthropic has raced to close the roughly $1.8 billion gap between its modest sales and enormous expenses.

The A.I. revolution, it is becoming clear in Silicon Valley, is going to come with a very big...