The NAHB/Wells Fargo Housing Market Index (HMI) is a monthly sentiment survey of members of the National Association of Home Builders (NAHB). The index measures sentiment among builders of U.S. single-family homes, and is a widely watched gauge of the U.S. housing sector. Since housing represents a large capital investment and spurs additional consumer spending on appliances and furnishings, housing market indices help to monitor the overall health of the economy.