Traditional banks have to hold liquid capital to back up their asset portfolios. The riskier the assets are, the higher the capital that is required to hold. To prevent bank insolvency, the Bank for International Settlements,located in Switzerland, sets the international rules for capitalization of banks. The most recent framework is called the Basel III rules. In addition to the Basel III regulation, the Federal Reserve sets additional rules for U.S. banks. In contrast, investment banks and hedge funds have fewer rules. Thus, they may have higher leverage levels than traditional banks.
At the start of the Great Recession, many investment banks had leverage ratios of 30 to 1, meaning that 30 dollars of assets had only 1 dollar of equity. Even a small reduction in the value of the assets wiped out the equity, making the financial institution insolvent.