Liu Peng, a real estate professor at Cornell University, talked about this history when talking with the author. At that time, the interest rate in the United States continued to decline for a long time, the housing ownership rate continued to rise, and the demand for home purchase was strong. This series of factors prompted the nationwide housing prices in the United States to continue to rise before 2007. Among them, financial derivatives based on mortgage loans began to be popular in the investment market, so under the strong demand of the investment market, investment banks began to package subprime loans into new products. At the same time, Bank of America relaxed its supervision and failed to realize the crisis in time. Since then, house prices have been rising, and after the price soared to the point of "not selling", the inflated bubble finally burst.

Richard Coase, consultant of the International Monetary Fund's global real estate observation project, believes that the so-called financial innovation in the United States led to excessive lending by lending institutions regardless of the solvency of buyers, which eventually led to the subprime mortgage crisis. Coase said that the asset securitization market in the United States gave birth to structured financial products such as mortgage-backed bonds (CDOs), and the holders' structure was complex, which made it impossible for regulators to judge where the systemic risk was when house prices fell.

After the bursting of the housing bubble, loans defaulted, the liquidity of financial markets tightened, the cost of borrowing increased, and the funds of many traditional enterprises broke, which affected wages, ability to pay and employment. In turn, it impacted the fundamental operation of the American economy that year.

Therefore, in 20 10, the United States promulgated the most severe financial regulatory reform bill since the Great Depression, namely Dodd-Frank Act. In this bill, it is clearly stipulated that mortgage lenders must keep 5% credit risk, thus forcing mortgage lenders to carefully examine the qualifications of loan applicants. Robert Bo, a senior researcher at Brookings, once pointed out that high down payment requirement is the best way to reduce mortgage default. According to reports, in order to further improve the mortgage policy and ensure that potential loan buyers have the ability to repay their mortgages, in June of 20 13, 13, the US Consumer Financial Protection Bureau issued the housing mortgage loan standard. This regulation prohibits high-risk lending practices, such as floating mortgage loans and allowing lenders to pay interest instead of principal for a period of time.