Which bank failure became the defining trigger of the 2008 global financial crisis?

The bankruptcy of Lehman Brothers became the defining trigger of the 2008 global financial crisis.

Lehman Brothers filed for Chapter 11 bankruptcy protection on September 15, 2008. It was the largest bankruptcy filing in U.S. history at that time, with hundreds of billions of dollars in assets. The failure caused severe stress in credit markets and accelerated a worldwide financial panic.

Lehman was not the only institution in trouble. Bear Stearns had been rescued earlier in 2008, while American International Group received government support shortly after Lehman failed. The crisis grew from interconnected problems involving U.S. housing, mortgage lending, securitized debt, leverage, and fragile financial institutions.