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The strange saga of sectors in September

Jay Kaeppel
2026-09-03
Herein, we examine the history of September performance for all 11 S&P 500 sectors. We also look more closely at mid-term Septembers and highlight the five worst September performers.

Key points:

  • We detailed in a previous note that the S&P 500 tends to perform poorly in September, but that results can vary widely from year-to-year
  • We also noted several sectors facing notable seasonal headwinds
  • In this note, we broaden the horizon and examine the performance of all 11 S&P 500 sectors during September since 1927
  • We also highlight mid-term election Septembers, and the five sectors that have shown the worst results of the past 99 Septembers

Sector performance during September

As detailed in this previous note, a) September has been the worst month of the year for stocks, and b) in any given September, anything can happen. As a result, investors sometimes face a September conundrum. Should I sell out of concern that stocks tend to perform poorly? Or should I just ride it out since win rates tend to be more of a coin flip? The reality is that each investor must answer those questions for themself. To help you decide, let's take a closer look at sector performance during September.

The table below summarizes the performance of each of the 11 S&P 500 sectors during September only, si

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Risk Disclosure: The information and tools provided are for research and analytical purposes only and are not intended as investment advice. Market analysis involves uncertainty, and outcomes may differ from expectations. Users should conduct their own due diligence and consider their individual circumstances before making any financial decisions. Past performance is not necessarily indicative of future results.

Hypothetical Performance Disclosure: Hypothetical performance results have many inherent limitations, some of which are described below. No representation is being made that any account will or is likely to achieve profits or losses similar to those shown; in fact, there are frequently sharp differences between hypothetical performance results and the actual results subsequently achieved by any particular trading program. One of the limitations of hypothetical performance results is that they are generally prepared with the benefit of hindsight. In addition, hypothetical trading does not involve financial risk, and no hypothetical trading record can completely account for the impact of financial risk of actual trading. for example, the ability to withstand losses or to adhere to a particular trading program in spite of trading losses are material points which can also adversely affect actual trading results. There are numerous other factors related to the markets in general or to the implementation of any specific trading program which cannot be fully accounted for in the preparation of hypothetical performance results and all which can adversely affect trading results.

Testimonial Disclosure: Testimonials appearing on this website may not be representative of other clients or customers and is not a guarantee of future performance or success.