if one or more of those tiny regional banks fail in the same way SVB did I don’t see why there wouldn’t be an issue as a customer of Mercury
it’s also unknown what percentage of these banks’ total deposits are Mercury deposits now. if it’s a lot then you have the same risk of a bank run on the Mercury side disproportionately impacting the solvency of the underlying bank
and the problem is you know nothing about the financial health of the small banks that are white label providers so how can you say you’re confident in the management of these individual banks that Mercury is contracting with? you don’t know anything about them.
so, if mercury has a 1M FDIC guaranteed, then you can move 1M per day through their systems with 100% guarantee, but the risk that a bank fails on one particular day is very small, so maybe you can move 10M a day through them, with effectively no risk.
10M a day is 3.5B a year. very few companies are doing transactions on that level, so mercury scales up very well.