Annualizing year-to-date (YTD) data allows you to compare current performance over different time periods. For example, if your portfolio is up 4 percent in the first five months of the year, it's hard to tell whether it's on track to beat the 10 percent return you achieved the previous year. Converting performance measures to an annual percentage lets you make a more meaningful overall comparison.
Follow the Formula
To annualize data, divide the current value by the initial investment value. Then, raise the result to 12 divided by the number of months that have passed. Third, subtract 1. Fourth, multiply by 100. For example, say that your portfolio was worth $1,000 at the start of the year and it's worth $1,040 five months later at the end of May. Divide $1,040 by $1,000 to get 1.04. Then, raise 1.04 to the 12/5, or 2.4th, power to get 1.0987. Third, subtract 1 from 1.0987 to get 0.0987. Fourth, multiply by 100 to find your annualized return would be 9.87 percent.