How Are Mortgage Rates Determined?

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The U.S. Federal Reserve and mortgage rates have a very close relationship, although two concepts exist about mortgages that many people, including those in the financial media, real estate, and lending professions, don't always understand completely. The first is how mortgage rates are determined, followed by how those mortgage rates are affected when the U.S. Federal Reserve Bank issues rate changes.

Even if you don't fully understand these concepts, you still stand to get a good rate on your home loan. In challenging markets with changing interest rates, however, it helps to know the basics so you can look out for your own financial welfare.

What Are Mortgage Rates Based On?

Contrary to popular belief, mortgage rates are not based on the 10-year Treasury note. They're based on the bond market, meaning mortgage bonds or mortgage-backed securities. When shopping for a new home loan, many people jump online to see how the 10-year Treasury note is doing, but in reality, mortgage-backed securities (MBS) drive the fluctuations in mortgage rates.

In fact, it is not unusual to see them move in completely different directions and, without professional guidance, that confusing movement could cause you to make make a poor financial decision.

Some bond market reporters mistakenly tie mortgage rates to the performance of the 10-year Treasury bond. Many of these financial reporters possess a broad knowledge of bond markets, but they are not mortgage experts and do not fully comprehend how mortgage interest rates are determined.

Mortgage loans are packaged into groups or bundles of securities and then sold in the bond market. The price of these bundled debt securities is driven by national and global news events, which also affects individual mortgage rates.

The graph below illustrates the 30-year fixed mortgage rate average from 2000 through today.

Understanding APR

You'll likely see APR any time you're looking at mortgage rates. APR stands for Annual Percentage Rate, and it's the interest rate that's applied to your monthly mortgage payment, plus additional fees. Say your monthly house payment has an interest rate of 4.75 percent, but your loan's APR is 5 percent. The difference is due to upfront or ongoing fees.

Calculating a Mortgage Rate

Interest rates on home loans are built up using an index based on the current market, such as the bond market, and a markup that represents the lender's profit. If you're looking at published rates, note that they tend to represent an average, and you may find that rates in your specific geographical area vary.

The rates you're offered will also be impacted by your credit score range. Lenders price your mortgage loan based on your risk profile.

If you have a great credit score, it's much less likely statistically that you'll default on your loan, so you'll get a lower interest rate. If you have a lower credit score, your lender will want more interest to compensate for the additional risk of you defaulting on the loan, so you'll have to pay a higher interest rate.

How the Fed's Actions Affect Mortgage Rates

When the Fed lowers the short-term discount rate to stimulate consumer spending on short-term credit, it affects credit card rates, some car loans and lines of credit. The short-term discount rate has little effect on long-term mortgage rates.

The market moves faster than you may expect—sometimes at lightning speeds. When investors spot a short-term stimulus, they bail out of the safe haven of bonds—or mortgage-backed securities—and put those dollars into stocks. When this happens, you'll see a rally in the stock market and a sell-off of mortgage-backed securities, both of which cause interest rates to go up.

The Reality of Fed Rate Cuts

When the Fed cuts interest rates, especially by a large or repeated percentage-point drop, people automatically assume that mortgage rates will fall. But if you follow mortgage rates, you will see that most of the time, the rates fall very slowly, if at all. Historically, when the Feds have dramatically cut rates, interest rates remain almost identical to the rates established months before the cut as they do months after the cut. The Fed’s moves aren’t totally irrelevant and do have a delayed and indirect impact on home loan rates.

When investors worry about inflation, this concern will push rates up. When Congress wants to stimulate action and raise money for a deficit, it will create more U.S. Treasuries for folks to buy. This added supply of new Treasuries can also cause rates to move higher.

Even more crucial is when a buyer is in the process of making a decision whether to lock a loan just before a Fed rate cut. Say a buyer is in a contract and is thinking the Fed is going to lower rates next week. The buyer might be tempted to wait before locking the loan—big mistake. When the Fed makes that big drop, say by 50 basis points or more, it actually can cause 30-year-fixed rates to initially spike. But then over time the rates generally level out or regain their losses—depending, of course, upon current market trends.

So, if a buyer is within three weeks of closing before an anticipated Fed cut, it's usually recommended to lock in ahead of the Fed rate cut to protect that original good interest rate.