A mortgage loan with an interest rate that can change periodically, typically based on an index, resulting in varying monthly payments over time. A mortgage loan with an interest rate that can change periodically, typically based on an index, resulting in varying monthly payments over time. A mortgage loan with an interest rate that can change periodically, typically based on an index, resulting in varying monthly payments over time. A mortgage loan with an interest rate that can change periodically, typically based on an index, resulting in varying monthly payments over time.