The U.S. financial crisis was not just caused by subprime mortgages, but also by risky financial innovations that made the system unstable. Asset securitization played a role in the crisis, but it was not the main cause. The American capital market can make financial problems worse, leading to a recession in the real economy. To prevent future crises, we need to control the negative effects of asset securitization, supervise financial innovation, and focus on making the financial market serve the real economy.