a money market fund holds 100% coverage for its deposits in short term high quality assets like T-bills and short AAA commercial paper. Not risk-free but a LOT less risky than the inherently unstable fractional reserve commercial banks with typically holds less than 10% of its deposits in liquid assets and the rest in long term and/or illiquid assets.
Discussion
even a treasury direct account is a better option for most corporations with large cash reserves than a commercial bank. it seems like it is amateur hour in silicon valley due to the "strings" that SVB put on its customers.
just like FTX: "want our money, then you have to accept our token and keep your deposits with us"