A warning is out that AI tools hunting for the best interest rate could pull money out of banks fast enough to break them — bad news for smaller banks and anyone holding large deposits.

• New apps link several of your bank accounts and move your cash to whichever bank pays the most, automatically and daily.
• Apollo's Torsten Slok says if most people do this, banks lose the cheap deposits they use to fund loans.
• Money that moves in seconds is the ingredient of a bank run: one attractive rate could drain several banks at once.
• Keeping deposits under the FDIC insurance limit at each bank matters more if this plays out.
• These financial apps grow faster than people expect, and an earlier collapse of a third-party partner to online banks already cost thousands of people their savings.

Outlook: Nothing breaks tomorrow, but expect more pressure on bank deposits and more attention to deposit insurance rules as these tools spread.