Big companies are spending so much on AI that many are now burning cash instead of generating it, a warning sign for investors watching this earnings season.

• Amazon posted a massive negative free cash flow swing, going from billions in positive cash a year ago to tens of billions negative now, driven by heavy AI spending.
• Alphabet (Google's parent) also burned cash the last two quarters in a row, though it's still cash-positive over the full year.
• Both Amazon and Alphabet are keeping or even raising their spending plans, meaning the cash burn isn't slowing down anytime soon.
• Smaller companies outside tech are struggling too — appliance maker Whirlpool, diagnostics company Quidel Ortho, and ATM maker Diebold Nixdorf all reported negative cash flow and cut their outlooks, citing weak demand and rising costs.
• Some of these companies even pulled their own financial forecasts, a sign they're unsure how bad things could get.

Outlook: Expect more companies to report similar cash problems in the coming months, with weaker earnings likely pressuring stock prices lower around early next year.