Why Mortgage Rates Jumped — Even Though Core Inflation Is Falling

Why Mortgage Rates Jumped — Even Though Core Inflation Is Falling

Mortgage rates had an extremely difficult week.

The 10-year Treasury yield broke through 4.80%, surged toward 5%, and mortgage-backed securities experienced a significant selloff.

That pushed mortgage rates to some of their highest levels of 2026.

Then something interesting happened Friday morning.

The August Consumer Price Index showed another relatively hot month for inflation — and bonds improved.

That sounds backwards.

It isn't.

Here's what's happening.

August Inflation Remains Too Hot for the Fed

Headline CPI increased 0.4% in August, matching expectations.

Year-over-year inflation remained at 3.4%.

Core CPI, which removes food and energy, increased 0.3% for the month. That was slightly hotter than expected.

The Federal Reserve wants inflation moving sustainably toward its 2% target, and these monthly numbers don't provide enough evidence that we've gotten there.

Markets are now pricing approximately an 85% probability that the Fed raises its benchmark rate by 25 basis points at its September 16 meeting.

So Why Did Bonds Improve?

This is the counterintuitive part.

The bond market hates inflation.

Long-term bonds become less attractive when investors believe inflation will remain elevated because inflation reduces the purchasing power of their future payments.

At this point, investors may actually prefer the Federal Reserve to raise short-term rates.

A Fed hike would signal that policymakers are serious about controlling inflation.

If investors believe tighter monetary policy will ultimately reduce future inflation, longer-term Treasury yields can actually decline.

That's one reason mortgage rates don't necessarily increase simply because the Fed raises the Fed Funds Rate.

The Fed controls an overnight interest rate.

Mortgage rates are much more closely connected to the bond market and expectations about future inflation, growth and monetary policy.

There Was Better News Inside CPI

The headline doesn't tell the entire story.

Core inflation actually declined from 2.5% to 2.4% year-over-year, its lowest reading of 2026.

Shelter increased only 0.26%.

Rent and Owners' Equivalent Rent both increased less than 0.2%.

Some of the month's inflation was concentrated in a relatively small number of categories.

Gasoline increased almost 4%.

Airfare increased approximately 2.7%, partly reflecting higher energy costs.

Education and communication services increased approximately 1.85%.

According to the analysis we're following, removing shelter, airfare and education/communication services leaves very little monthly core inflation.

That's encouraging.

The problem is that Federal Reserve officials may focus more heavily on the headline and monthly core readings.

The 5% Treasury Level Matters

The 10-year Treasury approached 5% Friday morning.

That's significant because yields around 5% represented the highs reached in 2023.

But there's an important difference between 2023 and today.

Mortgage rates are nearly one percentage point better today than when the 10-year Treasury was around similar levels in 2023.

Why?

Mortgage spreads have narrowed.

Mortgage rates aren't determined solely by the 10-year Treasury. The additional spread investors demand for owning mortgage-backed securities also matters.

That spread was unusually wide in 2023.

It has improved since then.

That's one reason today's mortgage market isn't quite as bad as the Treasury yield alone might suggest.

What Happens Next?

The Federal Reserve meets September 15–16.

Markets currently expect a 25-basis-point increase.

Fed Chair Kevin Warsh's comments following the decision may ultimately matter more to mortgage rates than the hike itself.

Investors will want to know whether this is:

A one-time move designed to reinforce inflation credibility,

or the beginning of another tightening cycle.

Next week also brings Retail Sales, housing data, Jobless Claims and additional employment information.

What Should Homebuyers Do?

For borrowers closing soon, this is not an environment where I'd recommend gambling on a large near-term rate improvement.

The market has broken through several important technical levels, inflation remains elevated and geopolitical risks continue to influence energy prices.

That doesn't mean buyers should stop buying.

It means financing strategy matters.

If the house and payment make sense today, we can protect the transaction and continue monitoring rates afterward.

Markets change.

Your financing strategy should be able to change with them.