what caused mortgage crisis
The subprime mortgage crisis was caused by hedge funds, banks, and insurance companies. The first two created mortgage-backed securities. The insurance companies covered them with credit default swaps. Demand for mortgages led to an asset bubble in housing.
The subprime mortgage crisis was also caused by deregulation. In 1999, the banks were allowed to act as hedge funds. They also invested depositors' funds in outside hedge funds. That's what caused the Savings and Loan Crisis in 1989, Many lenders spent millions of dollars to lobby state legislatures to relax laws.