The National Mortgage Crisis of the 1930s was a Depression-era crisis in the United States characterized by high-default rates and soaring loan-to-value ratios in the residential housing market. Rapid expansion in the residential non-farm housing market through the 1920s created a housing bubble inflated in part by ad hoc innovation on the part of the four primary financial intermediaries – commercial banks, life insurance companies, mutual savings banks, and Building & Loans (thrifts). As a result, the federal overhaul stemming from New Deal legislation gave rise to a paradigmatic shift in mortgage lending, popularizing longer-term maturity, fully amortizing mortgages and creating a thick secondary market for mortgage-related securities.