Morningstar assigns a Category Risk Level to each group of mutual funds that invest in the same types of assets. These scores range from 1 (for funds with the least amount of relative risk) to 10 (for funds with the greatest amount).
In determining the Category Risk Level, the scores based on the Morningstar Risk are reviewed by Morningstar’s Research Committee. The Committee reviews the preliminary output, and makes changes where necessary, to ensure that the final scores are logically consistent and are updated to reflect current market conditions.
How Morningstar calculates category risk scores
The first step is to determine the average Morningstar Risk for each category over the previous five years. Morningstar Risk is the difference between the Morningstar Return (excess total return over the risk free rate, adjusted for loads) and the Morningstar Risk Adjusted Return (excess total return over the risk free rate, adjusted for loads and risk). Risk is measured by the variations in a fund’s monthly total returns during the period, with greater risk leading to a lower risk-adjusted return. The Morningstar Return and Morningstar Risk Adjusted Returns for each category are found using an equal weighted average of the total returns of all the funds in the category for a certain time period.
The category’s Morningstar Risk is then used as the starting point for the Category Risk Level assignments. Assignments can be modified in one of two ways. One method of modification is by logic. For instance, if one municipal bond category falls just across the dividing line from another municipal bond category (even though both invest in very similar types of assets), both categories are adjusted so that they are given the same risk assignment. They may also be adjusted by judgment. One example of this would be Long-Short Market Neutral stock funds. Although these funds tend to show very low risk scores based solely on the variations in their returns, the complexity of their strategies suggests that they should receive a higher risk score than the raw data indicates. In this case, the Category Risk score is adjusted accordingly.