What Caused the 2008 Financial Crisis?

The Post-2001 Housing Boom & Predatory Subprime Origination

The 2008 Global Financial Crisis was the most severe economic disruption since the Great Depression of 1929, destroying over $20 trillion in global wealth [1,2]. The crisis was not an unpredictable "black swan" event, but the direct result of catastrophic structural flaws in mortgage origination, securitization, and shadow banking leverage [1,2,4].

Following the 2001 dot-com crash, low interest rates sparked a nationwide housing bubble [2]. Mortgage originators, unburdened by default risk because loans were immediately resold to Wall Street investment banks, abandoned underwriting standards [1,4]. Subprime, no-income-verification ("NINJA"), and adjustable-rate mortgages (ARMs) proliferated under the false premise that housing prices would rise indefinitely [1,4].

"Mortgage lenders abandoned underwriting standards because toxic loans were immediately securitized and sold to Wall Street."

Financial Engineering: MBS, CDOs & The AAA Rating Agency Conflict

Wall Street investment banks packaged thousands of individual mortgages into Mortgage-Backed Securities (MBS) and re-sliced them into Collateralized Debt Obligations (CDOs) [1,4,6]. Through mathematical correlation tranching models, financial engineers claimed that default risk was neutralized [6].

Credit rating agencies (Moody’s, Standard & Poor’s, Fitch)—paid directly by the banks issuing the bonds—awarded pristine AAA investment-grade ratings to toxic subprime CDO tranches, allowing pension funds and global banks to load their balance sheets with hazardous debt [1,4,6].

Shadow Banking & The Lehman Brothers Overnight Run

Non-depository investment banks—including Bear Stearns and Lehman Brothers—funded long-term illiquid CDO assets using short-term overnight repurchase (repo) agreements with leverage ratios exceeding 30:1 [1,2,5].

When nationwide housing defaults accelerated in 2007, subprime asset values evaporated, sparking an overnight run on the shadow banking system [2,5]. On September 15, 2008, Lehman Brothers filed for bankruptcy, freezing global commercial paper and interbank lending markets [3,5].