In its "Declaration of the Summit on Financial Markets and the World Economy," dated 15 November 2008, leaders of the Group of 20 cited the following causes:

During a period of strong global growth, growing capital flows, and prolonged stability earlier this decade, market participants sought higher yields without an adequate appreciation of the risks and failed to exercise proper due diligence. At the same time, weak underwriting standards, unsound risk management practices, increasingly complex and opaque financial products, and consequent excessive leverage combined to create vulnerabilities in the system. Policy-makers, regulators and supervisors, in some advanced countries, did not adequately appreciate and address the risks building up in financial markets, keep pace with financial innovation, or take into account the systemic ramifications of domestic regulatory actions.

• The United States has seen an increasing concentration of wealth to the detriment of the middle class and the poor with the younger generations being especially affected. The middle class dropped from 61% of the population in 1971 to 51% in 2011 as the upper class increased its take of the national income from 29% in 1970 to 46% in 2010. The share for the middle class dropped to 45%, down from 62% while total income for the poor dropped to 9% from 10%. Since the number of poor increased during this period the smaller piece of the pie (down to 9% from 10%) is spread over a greater portion of the population.^[108] The portion of national wealth owned by the middle class and poor has also dropped as their portion of the national income has dropped, making it more difficult to accumulate wealth. The younger generation, which would be just starting their wealth accumulation, has been the most hard hit. Those under 35 are 68% less wealthy than they were in 1984, while those over 55 are 10% wealthier.^[109] Much of this concentration has happened since the start of the Great Recession. In 2009, the wealthiest 20% of households controlled 87.2% of all wealth, up from 85.0% in 2007. The top 1% controlled 35.6% of all wealth, up from 34.6% in 2007.^[110] The share of the bottom 80% fell from 15% to 12.8%, dropping 15%.