In the weighted interest-sensitive gap methodology, all interest-sensitive assets and liabilities are given a weight based on their speed (sensitivity) relative to some market interest rate. Fed Funds loans, for example, have an interest rate which is determined in the market and which would have a weight of 1. All other loans, investments and deposits would have a weight based on their speed relative to the Fed Funds rate. To determine the interest-sensitive gap, the dollar amount of each type of asset or liability would be multiplied by its weight and added to the rest of the interest-sensitive assets or liabilities. Once the weighted total of the assets and liabilities is determined, a weighted interest-sensitive gap can be determined by subtracting the interest-sensitive liabilities from the interest-sensitive assets.
http://www.westga.edu/~rbest/international/finc4561/section2...