Bank Run

A bank run? Like a 10k? How fast does a bank run?

A bank run occurs when a large number of customers of the bank or another financial institution withdraw their funds simultaneously due to concerns about the bank's financial strength (liquidity/solvency).

Banks don't hold all the money customers deposit in that one place. That would be a piggy bank. A real bank takes the collective deposits of it customers, loans some to Pete for a house addition, some to Joan for a business loan, some to Joanie's daughter for grad school, etc. All with the intent to make money on its money, to derive a profit.

If all depositors demand their money back at once, the bank would have to foreclose on all the commitments made to other customers, which in all probability would be impossible, thus "breaking" the bank.