Subprime is the term used in the mortgage industry for a borrower with shaky credit. A prime borrower is one with good credit. As banks were looking for more customers in the mid-2000s, they began lending money to borrowers with worse credit than they generally lent to. Many of those loans began to go bad when the economy slowed and housing prices started to slide. Many of those loans had been bundled into securities, called mortgage-backed securities (MBS), with the cash flow from the homeowners' monthly payments going to investors. When the subprime borrowers started to default on their loans, the value of the securities sunk quickly. This created chaos in the market for mortgage-backed securities, which spread to the rest of the credit markets. In testimony before Congress, officials from the Federal Reserve noted the rapid rise of subprime lending. Sandra F. Braunstein,_Director of the Division of Consumer and Community Affairs, noted that in 1994, fewer than five percent of mortgage originations were subprime, but by 2005 about 20 percent of new mortgage loans were subprime. She said that the rise in subprime foreclosures resulted from a combination of economic conditions including rising interest rates and slowing house price growth. Until about 2005, borrowers with adjustable rate mortgages could cope with payment increases by refinancing or in some cases selling, because the hot real estate market kept pushing house prices up. But in 2006, mortgage interest rates hit four-year highs, the volume of home sales fell and the rate of house price appreciation slowed - in some cases home prices fell - leaving the most recent subprime borrowers with payment difficulties. Subprime borrowers with adjustable-rate mortgages (ARMs) started to struggle with delinquency and foreclosure rates.