Nasdaq-100 in September: seasonality and history
Since 1985, the Nasdaq-100 has risen in September in 55% of years (23 of 42), with an average return of −0.58% and a median of +0.61%. That makes September its #12 month of 12.
Average−0.58%
Years up55%
Best year1998 · +17.99%
Worst year2001 · −20.50%
The seasonal path through September
Cumulative sum of each day's average return through September, all years since 1985.
| Strongest days | Avg | Up |
|---|---|---|
| Sep 28 | +0.39% | 59% |
| Sep 11 | +0.39% | 67% |
| Sep 19 | +0.37% | 60% |
| Weakest days | Avg | Up |
|---|---|---|
| Sep 29 | −0.55% | 43% |
| Sep 17 | −0.53% | 53% |
| Sep 21 | −0.42% | 38% |
September in recent years
| Year | Nasdaq-100 in September |
|---|---|
| 2026 | +3.23% |
| 2025 | +5.40% |
| 2024 | +2.48% |
| 2023 | −5.07% |
| 2022 | −10.60% |
| 2021 | −5.73% |
| 2020 | −5.72% |
| 2019 | +0.76% |
| 2018 | −0.35% |
| 2017 | −0.16% |
Questions
Is September a bad month for the Nasdaq-100?
On average, yes: −0.58% since 1985, rising in 55% of years. But the range is wide, from −20.50% in 2001 to +17.99% in 1998, so an average is a tendency, not a forecast.
What are the strongest days in September?
Sep 28 (+0.39%, up 59% of years), Sep 11 (+0.39%, up 67% of years), Sep 19 (+0.37%, up 60% of years).