Approximately 80% of US mortgages issued to subprime borrowers were adjustable-rate
mortgages8 (ARMs). ARMs typically had a fixed interest rate for a period of two or three
years, after which time they reset to a much higher rate. An estimated one-third of ARMs
which originated between 2004 and 2006 had attractive or “teaser” interest rates of below 4%
which then increased significantly after two or three years, frequently to double the initial rate.
This meant that while the loan was affordable to the borrower at the initial rate, it may have
become unaffordable when the rate was reset. The benefit of ARMs for homeowners was that
the starter rates were lower than those of traditional, fixed-rate mortgages. That meant lower
(initial) monthly payments, making home ownership more affordable and allowing borrowers