You are about to purchaseyour first home and receive an advertisement regarding adjustable-rate mortgages (ARMs). The interest rate on the ARM is lower than that on a fixed rate mortgage. The advertisement mentions that there would be a payment cap on your monthly payments and you would have the option to convert to a fixed-rate mortgage. You are tempted. Interest rates are currently low by historical standards and you are anxious to buy a house and stay in it for the long term. Why might an ARM not be the right mortgage for you?