No, banks collateralizing mortgages caused it.

https://en.wikipedia.org/wiki/Collateralized_debt_obligation

> In the early 2000s, the debt underpinning CDOs was generally diversified, but by 2006–2007—when the CDO market grew to hundreds of billions of dollars—this had changed. CDO collateral became dominated by high risk (BBB or A) tranches recycled from other asset-backed securities, whose assets were usually subprime mortgages. These CDOs have been called "the engine that powered the mortgage supply chain" for subprime mortgages, and are credited with giving lenders greater incentive to make subprime loans, leading to the 2007–2009 subprime mortgage crisis.

It's hard to ignore the similarities.

The cause is always a failure of underwriting. That was true of the Savings and Loan Crisis, the Great Financial Crisis.

It feels like each bubble gets bigger.