---
title: "S&P 500 Monthly Seasonal Returns"
description: "Historical average S&P 500 monthly returns by calendar month from 1928 to 2024, including the September effect, January effect, & Sell in May seasonal patterns."
canonical: https://www.getswoopr.com/tables/returns/sp500-monthly-seasonal-returns/
source: "Swoopr Investment: https://www.getswoopr.com"
---

## Direct Answer



> The S&P 500 shows seasonal patterns: January, April, and November-December are historically the strongest months. September is historically the weakest month (-1.0% average). “Sell in May and go away” has statistical support but is inconsistent across individual years.








# S&P 500 Monthly Seasonal Returns



## Average S&P 500 monthly price return (1928-2024 approximate)



| Month | Average return | Std deviation | % positive years |
| --- | --- | --- | --- |
| January | +1.0% | ~5.5% | ~59% |
| February | -0.1% | ~4.3% | ~53% |
| March | +0.9% | ~4.4% | ~61% |
| April | +1.4% | ~4.1% | ~63% |
| May | +0.2% | ~4.0% | ~57% |
| June | +0.1% | ~4.3% | ~54% |
| July | +1.0% | ~4.5% | ~59% |
| August | +0.1% | ~4.4% | ~55% |
| September | -1.0% | ~4.9% | ~44% |
| October | +0.8% | ~5.3% | ~59% |
| November | +1.4% | ~4.0% | ~65% |
| December | +1.4% | ~3.6% | ~72% |



Source: [NYU Stern: Historical Returns](https://pages.stern.nyu.edu/~adamodar/New_Home_Page/datafile/histretSP.html). Data through 2024; last checked September 2026.



## Frequently asked questions



Is "Sell in May and go away" a real effect?

The "Halloween Effect" or "Sell in May" strategy has statistical support: the May-October period historically underperforms the November-April period. Academic research (Bouman and Jacobsen, 2002) found the effect in 36 of 37 countries studied. The S&P 500 has averaged approximately +2% from May-October vs. +7% from November-April. However, high year-to-year variability makes this unreliable for individual years. In some years (2020, 2021), May-October was excellent; in others, selling would have been wrong. After transaction costs and taxes, the strategy's edge is minimal.



What causes the September seasonal weakness?

September's historical weakness (-1.0% average) has several potential explanations: (1) mutual fund fiscal year-end tax-loss selling (many fund fiscal years end September 30); (2) return from summer with portfolio reviews and risk-off activity; (3) end of summer vacation reduces liquidity; (4) psychological back-to-work risk reassessment. The weakness is one of the most statistically consistent seasonal patterns across decades and international markets, but any individual September can be strongly positive (September 2010: +8.8%; September 1939: +16.9%).



Is the January Effect still a real phenomenon?

The January Effect (small-cap stocks outperforming in January) was well documented in academic literature through the 1980s. Since then, increased awareness and institutional arbitrage have largely eliminated it. Small-cap January returns are no longer systematically abnormal. However, a weaker version persists: year-end tax-loss selling depresses small-cap prices in December, with some mean reversion in January. The original broad-market January Effect has also become less reliable as markets have become more efficient.







## Cite This Page



If you reference this table in your own work, use the following citation format and add the date you accessed it:



> Swoopr Editorial Team. (2026). *S&P 500 Monthly Seasonal Returns*. Swoopr Investment. [https://www.getswoopr.com/tables/returns/sp500-monthly-seasonal-returns/](https://www.getswoopr.com/tables/returns/sp500-monthly-seasonal-returns/)



Check the figures against the primary sources listed under References before you rely on or republish them; the series they come from are revised.







## References



- [NYU Stern: Historical Returns](https://pages.stern.nyu.edu/~adamodar/New_Home_Page/datafile/histretSP.html)







[Swoopr Editorial Team](https://www.getswoopr.com/authors/swoopr-editorial-team/) produces independent investment education and research content.



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