Why do mortgage rates change?

If you've been following mortgage rates in order to pick the perfect time to refinance or to apply for a home loan, you may have noticed that rates fluctuate daily. Mortgage rates change for a variety of reasons, all related to current economic conditions and the willingness of investors to purchase mortgage-backed securities.

Mortgage investors

The simplest explanation--although not the only factors that determines mortgage rates--is that rates are closely tied to movements in bond markets. As bond prices rise, their yields fall, and it is these yields which influence mortgage rates up or down.

While some mortgage funds come from deposits held at banks and brokerages, most come from investors. Mortgage investors are interested in earning the highest possible interest rate (“yield”), while mortgage borrowers are looking for the lowest possible interest rate.  Yields need to be high enough to make the investment valuable, but low enough to attract borrowers.

Since mortgage investors are looking for a fixed-income investment, rates  increase or decrease  according to the competition for investors in  these and other bonds.

Mortgage rates and Treasury bonds

There is no specific link between mortgage rates and Treasury bonds, but the latter are often the benchmark for other bonds since they are backed by the federal government and considered “risk-free.” Since Treasury bonds are 100 percent guaranteed and mortgage bonds are not, mortgage rates are typically set a little higher to compensate for their higher risk.

The difference between Treasury bonds and mortgage rates varies according to market conditions and sometimes one will rise (or fall) faster than the other.

Mortgage rates and market forces

In a normal market, without government intervention, mortgage rates would depend to a great extent on supply and demand. For a time, the Federal Reserve and Treasury were purchasing mortgage-backed securities (MBS) from Fannie Mae, Freddie Mac and Ginnie Mae along with certain MBS from other investors, who wanted to sell some of their holdings and were not willing to buy any new MBS, clogging up the mortgage market.

Since the Federal Reserve stopped purchasing these securities, investor interest in new high-quality MBS has returned; this demand, coupled with a weak economy, low inflation and a very weak housing market are all serving to keep interest rates low.

For a much more detailed review of the factors that move mortgage rates, you'll want to read "What Moves Mortgage Rates? (The Basics)" our deeper dive into the topic.

Michele Lerner contributed to this answer.

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Keith Gumbinger
Keith Gumbinger
Mortgage Expert
Vice President, HSH.com
About Keith: Mortgage market observer and analyst with 35 years experience... (more)
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