Published by Invest America Daily
September has a reputation, and the numbers back it up: it’s the only calendar month with a negative average return for the S&P 500 going back nearly a century. For dividend investors specifically, understanding why — and how to think about it — matters more than trying to dodge the month entirely.
The Seasonality Is Real
Since 1928, the S&P 500 has produced an average return of roughly -1.17% in September, according to data from Bank of America, and the index has finished the month lower in 56% of years. Other measurement windows tell a similar story: since 1950, September has averaged around -0.6% to -0.7%, and over just the last five years, the average decline has been steeper — around -2.7%. August and September are, in fact, the only back-to-back months since 1945 that have both averaged negative returns for the S&P 500.
This year, there’s added reason for caution. Research from Carson Investment Research has found that when the S&P 500 gains more than 1% in August and notches five or more record highs — both true in 2026 — September has historically underperformed even more than usual.
Why September Tends to Be Weak
There’s no single confirmed explanation, but a few commonly cited factors include institutional portfolio rebalancing as money managers return from summer vacation, tax-loss harvesting ahead of year-end, and simply lower summer trading volumes giving way to more active — and sometimes more volatile — trading as fall begins. It’s worth being clear that these are theories, not established facts, and seasonality is a historical tendency, not a rule that repeats identically every year.
The Important Caveat: Trend Matters More Than Season
Seasonality research consistently points to one nuance that gets lost in the “September is scary” headlines: when the market enters September above its 200-day moving average — as it has in 2026 — the average September return has historically been meaningfully better, and positive more often than not, compared to Septembers that begin with the market already in a downtrend. In other words, the broader trend heading into the month has mattered more than the calendar date itself.
Why This Is Especially Relevant for Dividend Investors
Dividend-focused portfolios are often built specifically for periods like this. If September volatility does materialize, a portfolio generating steady income doesn’t require selling shares into a downturn to fund near-term cash needs — the dividend keeps arriving regardless of what the S&P 500 does that week. That’s a meaningfully different experience than watching a pure growth portfolio swing without any offsetting income.
This doesn’t mean dividend stocks are immune to a broad market pullback — they aren’t. But historically, lower-volatility, higher-quality dividend payers have tended to hold up better than the broader market during exactly this kind of seasonal turbulence, for the same reasons they’ve outperformed during other volatile stretches in 2026: steadier cash flows, established balance sheets, and less dependence on optimistic growth assumptions.
Practical Ways Dividend Investors Can Prepare
Resist the urge to sell in anticipation of seasonal weakness. Even in years when September lives up to its reputation, the S&P 500 has historically returned an average of 13.4% over the 12 months following a record high — meaning attempting to time an exit around one seasonally weak month has often cost investors more in missed gains than it saved in avoided losses.
Revisit your dividend quality checklist. This is a good moment to double-check the fundamentals discussed in dividend investing generally: payout ratios well under 100%, consistent free cash flow coverage, and a multi-year (ideally multi-decade) track record of dividend increases rather than just a high current yield.
Consider whether your dividend allocation matches your actual timeline. If you’re years from needing portfolio income, a market pullback is primarily a buying opportunity for dividend growth stocks at better prices — as long as the underlying businesses remain sound. If you’re closer to relying on that income, this is a good time to confirm your holdings are the steadier, lower-volatility type rather than higher-yield names that may cut payouts under stress.
Don’t confuse a seasonal statistic with a forecast. September has been positive in 44% of years historically — meaning “seasonally weak” describes a historical tendency across nearly a century of data, not a guaranteed outcome for any single year, including this one.
The Bottom Line
September’s reputation as the market’s weakest month is grounded in real, long-running data, and 2026’s specific setup — a strong August with multiple record highs — has historically been associated with even more pronounced September weakness. But the same data shows that a market trending higher into the month, as it is now, has tended to soften that seasonal effect. For dividend investors, the practical takeaway isn’t to sell and wait out the month — it’s to make sure your portfolio’s income quality is strong enough that seasonal volatility becomes background noise rather than a reason to panic.
This article is for general informational purposes only and does not constitute financial or investment advice. Seasonal patterns are historical tendencies, not guarantees of future performance. Consult a qualified financial advisor before making investment decisions.