摘要：本文着重从美国政府的政策和金融衍生品这两个方面对2008年的美国金融危机进行分析。前半部分主要分析美国政府的放松管制政策，后半部分阐述了金融衍生工具是如何导致这场全球性的危机。最后对上文所作的分析进行总结。
　　关键词：金融危机 放松管制 金融衍生工具
　　
　　1.introduction
　　the financial crisis in 2007-2008 is the biggest crisis since the great depression in 1929-1933. so called as sub-prime mortgage crisis, the u.s. financial industry, meet a tragic death, the five largest banks are wiped out, the relevant economic data continues to deteriorate, the prospect for the economy into a pessimistic expectation and inflationary pressures.
　　
　　2.analysis of the cause of the crisis
　　as alan greenspan put it: from the financial crisis we have seen the neo-liberal advocacy in order to "reduce the control of the financial markets, privatization narrow the government, reducing the maximum tax rates, liberalization of the international commodity and capital markets, "characterized by" american model "there is a big flaw.
　　since the "9.11" incident, the u.s. government began cutting the interest rates, the federal benchmark interest rate from 3% in the year all the way down in january 2003 to 1% of the lowest level in nearly 30 years, and maintained until june 2004. the government wanted to boost liquidity by increasing the united states remains in the doldrums of the economic situation, however, in these three years the policy of ultra-low interest rate environment, liquidity dramatically increased the u.s. real estate boom. due to the low interest rate, the housing market bubble boomed in america. more and more houses were sold, and most people could afford the house paying by bank loans. at the same time, the property-value bubble and the liquidity have contributed to the proliferation of subprime loans. this financial crisis stems from such a housing loan products - subprime mortgages, which i will analyze later. on the other hand, a series of acts were issued to remove the obstacles for the operation of investment banks and corporation m&a, such as`the glemm-leach-bliley act"and"the commodity futures modernization act`.
　　financial derivatives also played a role in this disaster. these financial instruments were and are a means of hedging and taking on risk. in 2001, the commodity futures modernization act, written with the help of the financial lobbyists, it banned the regulations of derivatives. once the act was done, the use of derivatives and financial innovations exploded dramatically after 2000. using derivatives, bankers could gamble on virtually anything. the most typical derivative is cdo; its full name is collateralized debt obligation, which combined thousands of mortgages and other loans. among the mortgages, the subprime that i mentioned accounted large amount of the cdo. subprime mortgages are loans for real estate that are granted to individuals who do not have the ability to obtain a prime mortgage. this means that the borrower's ability to repay the loan is questionable based on a number of criteria. so we can see that the cdo is not stable and qualified, to some degree. but because of the deregulation and moral hazard, bankers didn’t care about the quality but the quantities. the investment banks sold the cdo to investors as possible as they can. in this way, when home owners pay their mortgages, the money went to the investors all over the world. at the same time, the investment banks paid rating agencies to evaluate the cdo, and many of them were given aaa rating. in this system, lenders didn’t care anymore about whether a borrower can repay, and the investment banks didn’t care either. the more cdo sold, the more profits they earned. due to the moral hazard, the investment banks preferred subprime loans because they carried higher interest rates. this led to a massive increase in lending, and more and more borrowers were involved in expensive loans, but many of borrowers could not repay them. this system is just like a time bomb, which is the weapon that caused the crisis.

　　
　　3.conclusion
　　based on the above analysis, the origin of the financial crisis is monetary policy of u.s. government. and the abuse of derivatives and financial institutions’ moral hazard also lead it. although the financial crisis bought the us economy into disasters, the financial reform which is the main measures taken by us government to cope with the crisis have no rooted impact to the financial industry. the financial crisis will be alleviated but not eliminated because of the interest that is held by the wall street and the u.s. government.
　　
　　references:
　　[1] gary b. gorto, the subprime crisis [eb/ol]. nber working paper, 2008.
　　[2] jianshan ke, "u.s. financial crisis:reason.government intervention and lessons".<>, cumulatively, no 116, no.8, 2010