A "too big to fail" bank is a massive financial institution whose sheer size, interconnectedness, and systemic importance mean that its sudden bankruptcy or insolvency would trigger catastrophic domino effects throughout the entire domestic and global financial system. The collapse of such an institution would freeze credit markets, wipe out corporate payrolls, and cause severe economic depression. Because of these systemic risks, governments and central banks have historically intervened with emergency liquidity injections, capital guarantees, or taxpayer-funded bailouts to rescue these financial giants during severe economic crises, creating ongoing regulatory debates regarding moral hazard.