Mortgage brokers present homebuyers with loans from a variety of loan sources. Their income comes from the lender making the loan, just like with any other bank. Because they can tap a variety of lenders, they can shop on behalf of the borrower and achieve the best available terms. Despite legislation that could favor major banks, mortgage bankers and brokers keep the market competitive so the largest lenders must continue to compete on price and service. According to Don Burnette of Brightgreen Homeloans in Port Orange, Florida, "The mortgage banker and broker conduit is vital to maintain competitive balance in the mortgage industry. cWithout it, the largest lenders would be able to unduly influence rates and pricing, potentially hurting the consumer. Competition drives every organization in this industry to constantly improve on their performance, and the consumer is the winner in this scenario." 
The HMI is a weighted average of separate diffusion indices for these three key single-family series. The first two series are rated on a scale of Good, Fair and Poor and the last is rated on a scale of High/Very High, Average, and Low/Very Low. A diffusion index is calculated for each series by applying the formula “(Good-Poor+100)/2” to the present and future sales series and “(High/Very High – Low/Very Low + 100)/2” to the traffic series. Each resulting index is then seasonally adjusted and weighted to produce the HMI.