April may be the cruelest month for poets, but September is crueler for stock traders. September ranks as the worst performing month across all the major U.S. stock indices going back decades, according to the 2026 Stock Trader’s Almanac, compiled by Jeffrey Hirsch and Christopher Mistal. The Dow Jones Industrial Average has shrunk by an average of 0.8% in Septembers going back to 1950; the S & P 500 by 0.7% going back to the same year. The technology-heavy Nasdaq Composite has dropped an average of 0.9% during the month since 1971, and the small-cap Russell 2000 by 0.8% since 1979. .RUT 1M mountain Russell 2000 one-month. “Portfolio managers back after Labor Day tend to clean house in September,” Hirsch and Mistal write in the almanac. “S & P opened strong 18 of last 30 years but tends to close weak due to end-of-quarter mutual fund portfolio restructuring.” If trends continue this year, September will see a marked break from August, in which the S & P 500 has risen more than 2% and the Dow over 1%. U.S. midterm elections in November may add more volatility to markets in the next month or two. “Mid-term election years have historically brought volatility in September and October,” JC O’Hara, chief technical strategist at investment bank Roth, wrote in a Sunday note to clients. “We are currently seeing rotation into sectors that lagged over the first half of 2026, which we believe reflects defensive posturing heading into the fall.” The S & P 500 hit multiple all-time highs in August, driven by surging corporate profits. Pre-tax corporate profits jumped in the second quarter to $4.8 trillion, or 18% of national income . That’s the highest share since at least 1950 . August saw a blockbuster second-quarter earnings report from Nvidia , the company at the center of the ongoing investment push within the computing sector. While the company raised revenue guidance by more than Wall Street expected, it also reported a big uptick in accounts receivable and a concomitant drop in free cash flow. Financial markets will need to process the prospect of continued hostilities between the U.S and Iran in September, as well as higher-than-desired price levels in the new month The U.S. and Iran exchanged blows for the first time in over a month as the U.S. struck targets on Iranian Larak Island and Iran fired at U.S. targets in Jordan. The personal consumption expenditures price index rose by 3.7% in July , close to double the Federal Reserve’s target of 2%. The headline number was slightly higher than expected, though off a recent high of 4.1% in May. West Texas Intermediate crude oil hit a high of $86.79 per barrel on Monday, the highest level since Aug. 21 when WTI traded at $87.51.