History is repeating itself on Wall Street.

The Dow Jones Industrial Average on Tuesday clinched its worst performance during the first 10 days of September since 2008, according to Dow Jones Market Data. Both the S&P 500 and Nasdaq Composite posted their worst 10-day starts to the month since 2020.

In a curious coincidence, Tuesday also happened to be the 18th anniversary of the bankruptcy filing of Lehman Brothers — a pivotal development that kicked off the most acute phase of the 2008 financial crisis. The Dow finished September 2008 down 6%, before falling more than 14% that October, according to FactSet data.

That stocks have struggled so far this month shouldn’t come as a surprise. September has a reputation for being the worst month of the year for major U.S. equity indexes, and the data back this up. The table below from Dow Jones Market Data shows that September has seen the worst average performance of any calendar month for the Dow, the S&P 500, the Nasdaq Composite and the small-cap Russell 2000.

It is also the only calendar month where the average performance for all four indexes is negative. The chart below features data from different time frames: For the Dow, the average figure includes every year back to 1897.

“Historically September has been a bad month, so it’s no surprise that’s what we’re looking at,” said Mark Gibbens, chief investment officer at Gibbens Capital Management, during an interview with MarketWatch.

But to be sure, the calendar alone isn’t responsible for this month’s stock-market rockiness. Like unhappy families, each red September has been miserable for markets in its own way. This time around, rising oil prices and bond yields, coupled with growing worries about AI, have been largely to blame, Gibbens said.

With the Federal Reserve expected to hike interest rates on Wednesday, more pain for stocks could be ahead.

“On the one hand, we still have a relatively resilient labor backdrop, so consumers are benefiting from income growth month to month… but I don’t want to discount the weakness associated with a potential hawkish turn by the Fed, higher rates at the long end and higher gas prices,” said Kevin Gordon, head of macro research and strategy at the Schwab Center for Financial Research.

“To me, that all adds up to headwinds for risk assets — not necessarily winds that are strong enough to end the bull market, but certainly strong enough to engineer a bigger wave of volatility.”

Stocks also struggled in September 2020, September 2021 and September 2022. In September 2020, stocks moved lower after a torrid summer rebound rally that saw major indexes claw back their COVID-19-related losses. U.S.-China tensions and worries about a COVID stimulus package that had stalled in Congress were largely to blame. In 2021, the arrival of new COVID variants and signs of a weakening Chinese economy helped send stocks lower after another exuberant stretch.

In 2022, investors reacted to then-Fed Chair Jerome Powell’s warnings in a speech in Jackson Hole, Wyo., that households and businesses in the U.S. might experience some pain in the short term as he promised the central bank would continue with aggressive interest-rate hikes to tamp down inflation. Earlier in the summer, consumer-price inflation had reached its highest rate in 40 years.