"Derivatives are financial instruments that come in several different forms, including 'futures', 'options', and 'swaps'. A derivative is a contract that derives its value from some underlying asset at a designated point in time. The derivative may be tied to a physical commodity, a stock index, an interest rate, or some other asset. Derivatives played a role in the 2008 financial crisis in a variety of ways. The unmonitored buildup of derivatives positions in the largely unregulated 'over-the-counter' (OTC) market led many major financial institutions into large financial losses. Possibly the best-known example of such losses was the insurance giant American International Group (AIG), whose massive losses from selling credit-default swaps ultimately contributed to the need for government assistance. OTC derivatives, prior to the Dodd-Frank Wall Street Reform and Consumer Protection Act (Dodd-Frank Act; P.L. 111-203), were traded bilaterally rather than cleared through a clearinghouse, and no reporting trail existed, which created uncertainty during the crisis over the web of exposures to large derivatives losses. The Dodd-Frank Act aimed to address these policy concerns by bringing the swaps market into a regulatory framework based on that of the futures markets, which had long been regulated by the Commodity Futures Trading Commission (CFTC). Security-based swaps tied to equities or narrow-based credit indexes were placed under the jurisdiction of the Securities and Exchange Commission (SEC) within a similar framework."
CRS Report for Congress, R44351
Federation of American Scientists: http://www.fas.org/sgp/crs/index.html