The Cost of Savings Index. This index is exclusive to World Savings.

COSI is the most stable of all indices.

COSI is a World Savings unique index which is calcuated at the end of every month by using a weighted average interest rate paid by World Savings on their checking accounts, savings accounts, and CDs. It is published by the 15th of the following month.

The most important feature of an adjustable rate mortgage is the index that determines its rate. A stable index, such as COSI, helps keep your payment on a steady, more predictable path. Year after year,cosi has shown not to move up or down as rapidly as market interest rates.