(Bloomberg – September lived up to its reputation of being the worst month for stocks. Investors went into October hoping for a rebound. Instead, they’re getting a reminder of just how volatile the 10th month of the year can also be.

According to Bank of America Corp. (NYSE:), October has an average 59% increase in value and returns of around 0.4%. If September falls, equities can again struggle. This is why October has a 0.4% average decrease.

“Unfortunately, for those looking for upside mean reversion, a down September is a risk for October,” wrote Stephen Suttmeier, technical research strategist at Bank of America Securities. Though September tends to be a seasonally choppy period, “October can have bigger drawdowns based on the seasonality of intra-month moves.”

September, which saw the lose 4.8%, was the gauge’s worst month since March of last year. There are many things investors need to be concerned about. Stocks start the fourth quarter with political uncertainty over the debt ceiling, a energy crisis, and the possibility of the Federal Reserve withdrawing from pandemic bond buying. 

It is currently on track for its fourth consecutive decline after six sessions. The recent losses have been getting worse. A slide of 1% or more for the S&P 500 Monday would mark the third straight lower session with a drop of that magnitude. That hasn’t happened since September 2020, when the index tumbled near 10%, according to data from Ally Invest. The S&P 500 was down 1.7% as of 12:43 p.m. in New York.

“Investors are processing a slew of tricky headlines, like the debt ceiling negotiations and a spike in oil prices” said Lindsey Bell, chief investment strategist at Ally. “Add all that up, and it’s causing some market angst against the backdrop of a Federal Reserve planning to remove market support by the end of the year.”

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