Since 1926, U.S. large-cap stocks have lost an average 0.9% in September, according to data from Morningstar Direct.
September is the only month during that nearly century-long period in which investors experienced an average loss, according to Morningstar. They saw a profit in all other months.
For example, February saw a positive 0.4% return, on average. While that performance is the second-lowest among the 12 months, is still eclipses September’s by 1.3 percentage points. July reigns supreme with an average return of almost 2%.
The monthly weakness also holds true when looking just at more recent periods.
For example, the S&P 500 stock index has lost an average 1.7% in September since 2000 — the worst monthly performance by more than a percentage point, according to FactSet.
Historically, the last two weeks of September are generally the weakest part of the month, said Abby Yoder, U.S. equity strategist at J.P Morgan Private Bank.
“Starting next week is when it would [tend to get] get a little bit more negative, in terms of seasonality,” Yoder said.
For example, the 10 best trading days by percentage gain for the S&P 500 over the past three decades all occurred during recessions, according to a Wells Fargo analysis published earlier this year.
Plus, average large-cap U.S. stock returns were positive in September for half the years since 1926, according to Morningstar. Put another way: They were only negative half of the time.
As an illustration, investors who sold out of the market in September 2010 would have foregone a 9% return that month — the best monthly performer that year, according to Morningstar.
“It’s all just random,” said Edward McQuarrie, a professor emeritus at Santa Clara University who studies historical investment returns. “Stocks are volatile.”
“History shows this trading theory has flaws,” wrote Fidelity Investments in April. “More often than not, stocks tend to record gains throughout the year, on average. Thus, selling in May generally doesn’t make a lot of sense.”
Since 2000, the S&P 500 saw gains of 1.1% from May to October, on average,over the six-month period, according to FactSet. The stock index gained 4.8% from November to April.
Mutual funds seem to be “pulling forward” those tax-oriented stock sales into September more often, Yoder said.
I think there’s an element of these narratives feeding on themselves.
Abby Yoder
U.S. equity strategist at J.P Morgan Private Bank
Investor uncertainty around the outcome of the U.S. presidential election in November and next week’s Federal Reserve policy meeting, during which officials are expected to cut interest rates for the first time since the Covid-19 pandemic began, may exacerbate weakness this September, Yoder said.
“Markets don’t like uncertainty,” she said.
But ultimately, “I don’t think anybody has a good explanation for why the pattern continues, other than the psychological one,” McQuarrie said.
The Trump administration paused its plan to garnish Social Security benefits for those who have defaulted on their student loans — but says borrowers’ paychecks are still at risk.
“Wage garnishment will begin later this summer,” Ellen Keast, a U.S. Department of Education spokesperson, told CNBC.
Since the Covid pandemic began in March 2020,collection activity on federal student loans had mostly been on hold. The Biden administration focused on extending relief measures to struggling borrowers in the wake of the public health crisis and helping them to get current.
The Trump administration’s move to resume collection efforts and garnish wages of those behind on their student loans is a sharp turn away from that strategy. Officials have said that taxpayers shouldn’t be on the hook when people don’t repay their education debt.
“Borrowers should pay back the debts they take on,” said U.S. Secretary of Education Linda McMahon in a video posted on X on April 22.
Here’s what borrowers need to know about the Education Department’s current collection plans.
More than 450,000 federal student loan borrowers age 62 and older are in default on their federal student loans and likely to be receiving Social Security benefits, according to the Consumer Financial Protection Bureau.
The U.S. Department of Education is seen on March 20, 2025 in Washington, DC. U.S. President Donald Trump is preparing to sign an executive order to abolish the Department of Education.
Win Mcnamee | Getty Images News | Getty Images
The U.S. Department of Education is pausing its plan to garnish people’s Social Security benefits if they have defaulted on their student loans, a spokesperson for the agency tells CNBC.
“The Trump Administration is committed to protecting Social Security recipients who oftentimes rely on a fixed income,” said Ellen Keast, an Education Department spokesperson.
The development is an abrupt change in policy by the administration.
The Trump administration announced on April 21 that it would resume collection activity on the country’s $1.6 trillion student loan portfolio. For nearly half a decade, the government did not go after those who’d fallen behind as part of Covid-era policies.
The federal government has extraordinary collection powers on its student loans and it can seize borrowers’ tax refunds, paychecks and Social Security retirement and disability benefits. Social Security recipients can see their checks reduced by up to 15% to pay back their defaulted student loan.
More than 450,000 federal student loan borrowers age 62 and older are in default on their federal student loans and likely to be receiving Social Security benefits, according to the Consumer Financial Protection Bureau.
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The massive package of tax cuts House Republicans passed in May is expected to increase the U.S. debt by trillions of dollars — a sum that threatens to torpedo the legislation as the Senate starts to consider it this week.
The Committee for a Responsible Federal Budget estimates the bill, as written, would add about $3.1 trillion to the national debt over a decade with interest, to a total $53 trillion. The Penn Wharton Budget Model estimates a higher tally: $3.8 trillion, including interest and economic effects.
Rep. Thomas Massie of Kentucky was one of two Republicans to vote against the House measure, calling it a “debt bomb ticking” and noting that it “dramatically increases deficits in the near term.”
“Congress can do funny math — fantasy math — if it wants,” Massie said on the House floor on May 22. “But bond investors don’t.”
A handful of Republican Senators have also voiced concern about the bill’s potential addition to the U.S. debt load and other aspects of the legislation.
“The math doesn’t really add up,” Sen. Rand Paul, R-Kentucky, said Sunday on CBS.
The legislation comes as interest payments on U.S. debt have surpassed national spending on defense and represent the second-largest outlay behind Social Security. Federal debt as a percentage of gross domestic product, a measure of U.S. economic output, is already at an all-time high.
The notion of rising national debt may seem unimportant for the average person, but it can have a significant impact on household finances, economists said.
“I don’t think most consumers think about it at all,” said Tim Quinlan, senior economist at Wells Fargo Economics. “They think, ‘It doesn’t really impact me.’ But I think the truth is, it absolutely does.”
Yields (i.e., interest rates) for long-term Treasury bonds are largely dictated by market forces. They rise and fall based on supply and demand from investors.
The U.S. relies on Treasury bonds to fund its operations. The government must borrow, since it doesn’t take in enough annual tax revenue to pay its bills, what’s known as an annual “budget deficit.” It pays back Treasury investors with interest.
If the Republican bill — called the “One Big Beautiful Bill Act” — were to raise the U.S. debt and deficit by trillions of dollars, it would likely spook investors and Treasury demand may fall, economists said.
Investors would likely demand a higher interest rate to compensate for the additional risk that the U.S. government may not pay its debt obligations in a timely way down the road, economists said.
Interest rates priced to the 10-year Treasury “also have to go up because of the higher risk being taken,” said Philip Chao, chief investment officer and certified financial planner at Experiential Wealth based in Cabin John, Maryland.
Moody’s cut the U.S.’ sovereign credit rating in May, citing the increasing burden of the federal budget deficit and signaling a bigger credit risk for investors. Bond yields spiked on the news.
A fixed 30-year mortgage would rise from almost 7% to roughly 7.6%, all else equal — likely putting homeownership further “out of reach,” especially for many potential first-time buyers, he said.
The debt-to-GDP ratio would swell from about 101% at the end of 2025 to an estimated 148% through 2034 under the as-written House legislation, said Kent Smetters, an economist and faculty director for the Penn Wharton Budget Model.
“But it’s not going out on too much of a limb to suggest financial markets the last couple years have grown increasingly concerned about debt levels,” Quinlan said.
Absent action, the U.S. debt burden would still rise, economists said. The debt-to-GDP ratio would swell to 138% even if Republicans don’t pass any legislation, Smetters said.
But the House legislation would be “pouring gasoline on the fire,” said Chao.
“It’s adding to the problems we already have,” Chao said. “And this is why the bond market is not happy with it,” he added.