Both June and July 2026 saw SPX close lower.

The S&P 500 declined 1.09% in June, measured on a calendar-month, close-to-close price-return basis, excluding dividends. It declined a marginal 0.13% in July.

Seasonality for those two months is generally favorable, and it is relatively uncommon for both months to be down in the same calendar year. Since 1950, this has occurred only 14 times (including this year), or about 18% of the years studied.

Since 1950, August and September have been two of the seasonally weakest months, ranking third worst and worst, respectively.

In this analysis, I decided to see how August and September have fared when June and July had already slipped.

The following table, covering 1950–2025, gives us an answer.

Sources: Quantifiable Edges, market data​

After lower closes in both June and July, August has generally been a toss-up. Sometimes it produced a bit of a rebound, and sometimes it didn’t.

But regardless of whether August rebounded, September’s numbers look pretty terrible. Eleven of the 13 Septembers closed lower, many of them by sizable amounts.

This seems worth keeping in mind as we consider other intermediate-term evidence that emerges over the next few weeks.

This is an edited version of an article that was first published by Quantifiable Edges on Aug. 3, 2026.

The opinions expressed in this article are those of the author and the sources cited and do not necessarily represent the views of Proactive Advisor Magazine. This material is presented for educational purposes only.