Deregulation was one of the causes of the 2008 financial crisis. Mortgage-backed securities are derivatives based on mortgages. Another financial invention, credit default swaps, help ensure their security. All of these were traded on the secondary market until 2006. In 2006, house prices began to decline. No one was knowledgeable enough to value mortgage-backed securities when the underlying mortgages began to default. Due to the high number of defaults, businesses that guaranteed the debt, such as American International Group Inc. (AIG), ran out of money.