What is shaky banking during the great depression

Another phenomenon that compounded the nation's economic woes during the Great Depression was a wave of banking panics or “bank runs,” during which large numbers of anxious people withdrew their deposits in cash, forcing banks to liquidate loans and often leading to bank failure.

Meaning the vast majority of American bankers followed established banking practices, but with no government regulation of the banking system, some bankers invested depositors’ money in shaky investments
Banks also lent consumers more than they could afford to repay
This vest over extension of credit made the entire U.S. economy extremely vulnerable