bank run

A bank run occurs when a large number of customers simultaneously withdraw their deposits because they fear the bank might fail or run out of money. Since banks usually keep only a fraction of deposits on hand and lend out the rest, a sudden surge in withdrawals can deplete their cash reserves quickly. This can cause the bank to actually face financial difficulties or collapse, even if it's otherwise healthy, simply because of the loss of confidence. Essentially, a bank run is driven by panic and can become a self-fulfilling crisis.