While money funds are not strictly gauranteed or insured, the 85% invested heavily in government securities put up some stark competition for bank deposits that have lagged central bank policy rate rises over the past 18 months - causing much political ire in countries such as Britain.
But, in contrast to money funds, the average rate across all of them, according to the Federal Deposit Insurance Corporation, is still just 0.37%.
That's now changing due to safety and insurance fears at smaller banks stateside - as well as the compelling alternative at money funds that appear safer against that backdrop.
Of this trillion, half went to government money market funds and the other half to larger banks, they reckoned.
Noting that some $7 trillion of U.S. bank deposits remained uninsured, the JPM team concluded: "A FDIC guarantee of all U.S. bank deposits would certainly help, but it might not be enough to completely stop this deposit shift."