Understanding Mortgage Rates

Understanding Mortgage Rates

Who sets mortgage rates? Why do rates change? How often do rates change? What is a Mortgage Backed Security (MBS)? These are some of the questions we are often asked by our clients and following is a brief explanation of the MBS market and how it works.

Mortgage loan interest rates, and the corresponding fees or points charged for various rates, are driven by the prices of Mortgage Backed Securities (MBS). While lenders, in effect, set their own mortgage rates, how those rates are set is driven largely by the then current prices of Mortgage Backed Securities. MBS are actually pools, or groups, of mortgages packaged into securities for sale in the secondary market. One security may, for example, be made up of 500 loans totaling $75,000,000. These MBS are traded in markets in a manner very similar to stocks and other fixed income securities, and what investors will pay for these drives interest rates.

Direct lenders originate loans, and wholesale and correspondent lenders purchase loans, from Mortgage Brokers or smaller lenders, most often with the intent to resell those loans into the secondary market, packaging them into MBS. So the going price in the secondary market for loans at various interest rates influences the rates and prices a lender will offer to the public or a Mortgage Broker. Although lender and wholesaler rate sheets are typically issued no more than a couple of times each day, the value of the mortgages, or the price of MBS, and consequently the price (points) for a certain interest rate, is actually constantly changing.

Unlike purchasing or selling stock, where the price is whatever it is at the moment you make the trade, wholesale and correspondent lenders generally issue a rate sheet setting forth their rates and corresponding points/premiums for those rates, and honor those rates, until the change in MBS prices reaches a certain threshold, before passing new prices on to their customers in the form of a new rate sheet. Typically lenders will issue new rate sheets as prices move more than 4/32nds to 8/32nds, or 0.125% to 0.25% points.