September, October, and November Seasonality: What Fall Markets Really Tell Investors

Fall market seasonality gets talked about every year, especially when investors start worrying about September weakness and October volatility.

Mark Yegge’s message is more practical: seasonality can be useful information, but it should not become a trading system by itself. The better approach is to treat the calendar as one data point while focusing on market momentum, risk management, and income generation.

Key Takeaways

Why Fall Seasonality Gets So Much Attention

Mark recently reviewed fall market seasonality for his mastermind group after a subscriber asked him to study what typically happens in September, October, and November.

The question is important because many investors carry strong assumptions about this part of the year. September is widely viewed as difficult. October is often associated with major crashes. November is less feared, but not always understood as a historically strong month.

Mark’s conclusion is that the fall quarter is mixed. September drags down the average, October is better than its reputation, and November has historically been one of the strongest periods of the year.

September: The Historical Underperformer

According to Mark’s study of the S&P 500 over the last 75 years, September is the weakest month on average. He describes it as the only negative month of the year across that long-term study.

That does not mean every September is bad. Mark makes the point that averages are shaped by outliers, and a handful of difficult Septembers can pull the average lower. He also notes that the average September decline is not even a full 1%.

His takeaway is practical: September may deserve respect, but it is not a reason to automatically abandon the market. A seasonal tendency is information, not a complete trading plan.

October: Not as Bad as Investors Think

October has a rough reputation because some of the most famous market crashes happened during that month. Mark specifically mentions October 1987 and the 1929 crash as part of why investors often view October with suspicion.

But based on the seasonal data Mark reviewed, October is not the worst month. It may have a higher typical range and more emotional baggage, but its average return is better than many investors assume.

That distinction matters. Volatility and directional weakness are not the same thing. A month can feel stressful without being consistently negative on average.

November: The Strongest Month in Mark’s Study

November stands out in Mark’s research. He identifies it as the strongest month on average, with a 1.82% average return in the S&P 500 study he reviewed.

He also notes that November begins the historically strongest six-month period for the market. December follows closely in his ranking, with a 1.49% average return, while April comes in near the top at 1.46%.

This is why Mark views the fall period as a mixed bag rather than a simple danger zone. September may be weak, October may be misunderstood, and November may provide a seasonal tailwind.

The Fall Quarter in Context

When Mark combines September, October, and November, the average return is 0.67%. For the other nine months, the average is 0.76%. In other words, the fall period is somewhat weaker, but not dramatically different.

The reason is simple: September pulls the fall average down, while November helps offset that weakness. October sits in the middle with a reputation that is often worse than the actual long-term data.

Mark also notes that the Dow Jones data tells a similar story to the S&P 500 research he reviewed, which gives the seasonal pattern more context.

Why Mark Does Not Believe in Calendar Timing

Mark is clear that he believes in market timing, but not calendar timing. That is an important distinction.

Calendar timing means making trading decisions because a month has a reputation. Examples include “sell in May and go away,” the January effect, or assuming October must be dangerous. Mark views those ideas as too simplistic.

Market timing, in Mark’s framework, means paying attention to momentum, broader market direction, and the actual condition of the market. He notes that roughly 70% of a stock’s direction comes from the direction of the overall stock market, which is why his Market Pulse signals matter.

Where Covered Call Income Fits

The Cash Flow Machine system focuses on generating income by selling options, including covered calls and selling puts. Mark compares stock positions to a piece of real estate: the shares are the asset, and the option premium is the income generated from that asset.

That is why seasonality matters differently inside an income strategy. If a month is slightly weak or choppy, the investor may still be bringing in income from option premium.

This does not remove risk. Stocks can still decline, and past averages do not predict the future. But Mark’s point is that income generation gives investors a different way to approach periods when the market is uneven.

Lessons From the Seasonality Study

Mark highlights several important lessons from the data. First, averages are not a trading system. They are only data points. Second, past performance does not guarantee what will happen next. Third, price returns and total returns are not always the same.

He also stresses that volatility is not the same as directional momentum. A month may have larger swings, but that does not automatically mean it is a bad month to own stocks or run an income strategy.

The biggest mistake would be to skip an entire month simply because of a seasonal reputation. Mark’s approach is to use the data, respect the risks, and still let the market’s actual condition lead the decision-making process.

What Traders Should Watch

Cash Flow IQ and the Role of Market Timing

Mark also discusses Cash Flow IQ, an AI implementation layer designed to support market timing on both individual stocks and the broader market.

The purpose is not to predict a month because of a calendar pattern. The purpose is to evaluate the market’s actual condition and use that information as part of a more disciplined process.

That fits the broader Cash Flow Machine philosophy: use data, use tools, use income strategies, and avoid making emotional decisions based on headlines or seasonal assumptions.

Wealth Accelerator Live: Build the Plan in Person

Mark also invited investors to Wealth Accelerator Live in Clearwater Beach, Florida, from October 30 through November 1. The event is designed as a hands-on workshop where attendees bring their laptops and build trading plans around cash flow strategies.

The focus includes written trading plans, stock outlooks for the rest of the year, and AI implementation through Cash Flow IQ. Mark emphasizes that the event is intentionally small so attendees can work directly in the room.

Learn More About the Event

The Bottom Line

September has historically been weak, October’s reputation is worse than its long-term average, and November has historically been a strong month. That is useful information, but Mark does not believe it should become a calendar-based trading system.

The better approach is to use seasonality as one data point, then focus on market momentum, stock quality, income generation, and discipline.

In Mark’s view, the goal is not to predict September, October, or November perfectly. The goal is to build a process that can help investors respond intelligently, generate income where appropriate, and avoid letting seasonal slogans drive portfolio decisions.