How often the S&P 500 rises and falls in a month or a year, and what it costs to miss its best months.
Key findings
- With dividends, the S&P 500 rose in 66% of months and in 30 of the 37 full years from 1989 to 2025.
- The worst year was 2008 (−37.0%) and the best 1995 (+37.6%).
- Missing the 10 best months would have turned $10,000 into $245,595 instead of $660,702.
How we calculated it
We calculate each month's return from the S&P 500's monthly closes, and each calendar year's from December to December, using only full years. We use both series without mixing them: with dividends reinvested, from January 1988, and without dividends, from December 1927.
Months and years in figures
| With dividends (1988–2026) | Without dividends (1927–2026) | |
|---|---|---|
| Months analysed | 465 | 1,186 |
| Positive months | 66% | 60% |
| Best month | +12.8% (Apr 2020) | +39.1% (Aug 1932) |
| Worst month | −16.8% (Oct 2008) | −29.9% (Sep 1931) |
| Full years | 37 | 98 |
| Positive years | 81% | 67% |
| Best year | +37.6% (1995) | +45.0% (1954) |
| Worst year | −37.0% (2008) | −47.1% (1931) |
| Median year | +15.8% | +11.6% |
Negative months are common: about one in three with dividends. Negative years are much less common, but they still come: with dividends, 1990, 2000, 2001, 2002, 2008, 2018 and 2022.
Every year, one by one
The cost of missing the best months
$10,000 invested in the S&P 500 with dividends at the end of January 1988 was worth $660,702 in October 2026. If instead of staying invested you had missed the best months (for example, by selling in fear and coming back late), the result changes a lot:
| If you missed… | 10,000 became | Annual return |
|---|---|---|
| No months | 660,702 | 11.42% |
| The 5 best months | 386,461 | 9.89% |
| The 10 best months | 245,595 | 8.61% |
| The 20 best months | 109,244 | 6.36% |
The best months tend to come very close to the worst: the best month in the series with dividends was April 2020, right after the March 2020 fall. People who sell in a fall often miss the recovery too.
Are some months better than others?
| Month | Share positive | Median return |
|---|---|---|
| January | 61% | +1.60% |
| February | 56% | +0.93% |
| March | 67% | +1.24% |
| April | 74% | +1.34% |
| May | 77% | +1.64% |
| June | 62% | +0.29% |
| July | 62% | +1.76% |
| August | 62% | +0.66% |
| September | 51% | +0.02% |
| October | 62% | +1.91% |
| November | 76% | +2.87% |
| December | 79% | +1.44% |
September has been the weakest month in both series (with dividends, positive only 51% of the time), but the differences between months are small compared with how much each month varies. It is not a rule you can use to time the market: the past is no guarantee it will repeat.
What it means for you
Falls over a month or a year are normal, and the best months arrive without warning. That is why staying invested steadily usually works better than trying to get in and out at the right moment. Only invest money you can leave alone for many years, and keep a separate emergency fund so you never have to sell at the worst time.