Answer:
large banks whose failure would start a widespread panic in the financial system.
Step-by-step explanation:
A bank run can be defined as a situation where bank clients or depositors make withdrawals of their money simultaneously from banks as a result of being scared or afraid the depository institution will run out of cash (bankruptcy) and become insolvent.
In order to counter the problem with bank runs, the Federal Deposit Insurance Corporation (FDIC) was established on the 16th of June, 1933.
Furthermore, to avoid bank runs or other financial institutions from being insolvent, the Federal Reserve (Fed) and Central banks (lender of last resort) are readily accessible and available to give monetary funds to these institutions when they're running out of money and as well as regulate their activities.
Hence, the government's too-big-to-fail policy applies to large banks whose failure would start a widespread panic in the financial system.