The S&P 500 is closing out 2025 with a rare and powerful show of momentum.
As of Dec. 26, the benchmark index is up nearly 1% for the month, positioning itself for an eighth consecutive month of gains — a streak not seen since 2017 and achieved only a handful of times in the post-war era.
The index of the 500 largest U.S. companies, tracked by the Vanguard S&P 500 ETF (NYSE:VOO), still has three trading sessions left before the year ends. If it holds onto these gains, the rally that began last May will officially extend into one of the market’s more exclusive historical clubs.
After such an impressive run, it’s natural for investors to wonder whether this is the moment to take profits.
But history suggests that such extended winning streaks have often led to continued strength rather than abrupt reversals.
Eight Green Months? The S&P 500 Has Been Here Only 10 Times Before
According to data compiled by Carson Investment Research analyst Ryan Detrick, the S&P 500 has logged eight or more consecutive monthly gains only 10 times in the post-war period.
That scarcity alone makes the current setup notable. What matters more is what followed those moments.
While the immediate month following such streaks has been a coin flip — with average returns near flat and gains occurring about 50% of the time — the picture improves meaningfully as the time horizon extends.
Three months after an eight-month winning streak, the S&P 500 delivered an average gain of 4.3%. That is nearly double the typical three-month return across all periods.
Even more striking, the index rose nine times out of 10. The lone exception came after November 1980, when stocks fell 6.6% over the next three months.
The trend strengthens further over six months.
Average gains climbed to 6.6%, well above the market’s long-term six-month average of 4.5%. Median returns reached 7.8%, and once again, nine of the 10 historical cases produced positive results.
Looking out a full year, the data remains supportive.
The S&P 500 posted average gains of 11.5% in the 12 months following these extended streaks, topping its long-term annual average of 9.2%. The frequency of gains — eight out of 10 — also exceeded the typical post-war win rate of roughly 73%.
While no historical pattern guarantees future outcomes, the takeaway is clear: prolonged momentum has often reinforced investor confidence rather than undermined it.
For investors, the market’s rare eight-month run may be less a signal to retreat — and more a reminder of how durable strong trends can be.
| Streak End Date | Months Up | Next Month | Next 3 Months | Next 6 Months | Next Year |
|---|---|---|---|---|---|
| 2/28/1950 | 11 | 0.4% | 9.1% | 7.0% | 26.6% |
| 4/30/1954 | 11 | 3.3% | 9.3% | 12.1% | 34.3% |
| 10/31/1958 | 11 | 2.2% | 8.0% | 12.2% | 12.1% |
| 7/31/1964 | 8 | -1.6% | 2.0% | 5.3% | 2.5% |
| 11/28/1980 | 8 | -3.4% | -6.6% | -5.6% | -10.1% |
| 3/31/1983 | 9 | 7.5% | 9.9% | 8.6% | 4.1% |
| 7/31/1995 | 8 | 0.0% | 3.5% | 13.2% | 13.9% |
| 6/28/1996 | 8 | -4.6% | 2.5% | 10.5% | 32.0% |
| 1/31/2007 | 8 | -2.2% | 3.1% | 1.2% | -4.2% |
| 11/30/2017 | 10 | 1.0% | 2.5% | 2.2% | 4.3% |
| 12/31/2025* | 8* | ? | ? | ? | ? |
| Metric | Next Month | Next 3 Months | Next 6 Months | Next Year |
|---|---|---|---|---|
| Average | 0.3% | 4.3% | 6.6% | 11.5% |
| Median | 0.2% | 3.3% | 7.8% | 8.2% |
| Higher | 5 | 9 | 9 | 8 |
| Count | 10 | 10 | 10 | 10 |
| % Higher | 50.0% | 90.0% | 90.0% | 80.0% |
| Metric | Next Month | Next 3 Months | Next 6 Months | Next Year |
|---|---|---|---|---|
| Average | 0.7% | 2.2% | 4.5% | 9.2% |
| Median | 1.0% | 2.6% | 4.9% | 10.4% |
| % Positive | 60.7% | 66.0% | 70.1% | 73.8% |
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