Why Do Mortgage Rates Change?
To understand why mortgage rates change we must first ask the more general question, "Why do interest rates change?" It is important to realize that there is not one interest rate, but many interest rates!
Interest-rate movements are based on the simple concept of supply and demand. If the demand for credit (loans) increases, so do interest rates. This is because there are more buyers, so sellers can command a better price, i.e. higher rates. If the demand for credit reduces, then so do interest rates. This is because there are more sellers than buyers, so buyers can command a lower better price, i.e. lower rates. When the economy is expanding there is a higher demand for credit, so rates move higher, whereas when the economy is slowing the demand for credit decreases and so do interest rates.
This leads to a fundamental concept:
A major factor driving interest rates is inflation. Higher inflation is associated with a growing economy. When the economy grows too strongly, the Federal Reserve increases interest rates to slow the economy down and reduce inflation. Inflation results from prices of goods and services increasing. When the economy is strong, there is more demand for goods and services, so the producers of those goods and services can increase prices. A strong economy therefore results in higher real-estate prices, higher rents on apartments and higher mortgage rates.
Mortgage rates tend to move in the same direction as interest rates. However, actual mortgage rates are also based on supply and demand for mortgages. The supply/demand equation for mortgage rates may be different from the supply/demand equation for interest rates. This might sometimes result in mortgage rates moving differently from other rates. For example, one lender may be forced to close additional mortgages to meet a commitment they have made. This results in them offering lower rates even though interest rates may have moved up!
There is an inverse relationship between bond prices and bond rates. This can be confusing. When bond prices move up, interest rates move down and vice versa. This is because bonds tend to have a fixed price at maturitytypically $1000. If the price of the bond is currently at $900 and there are 10 years left on the bond and if interest rates start moving higher, the price of the bond starts dropping. The higher interest rates will cause increased accumulation of interest over the next 5 years, such that a lower price (e.g. $880) will result in the same maturity price, i.e. $1000.