Seasonal Tendencies
In plain English. Seasonality refers to periods when markets, sectors or stocks tend to show recurring performance patterns driven by annual economic, corporate and behavioural cycles. This page shows what a market usually does month by month — every year since 1992 is set to zero on January 1 and averaged into one typical path, then this year is drawn on top so you can see whether the tape is following its normal rhythm, running ahead of it, or fighting it.
How to read it. The thin grey line is the typical year. The heavy black line is now. When this year runs above the typical path, the tape is stronger than its own base rate; when it runs below, something idiosyncratic is weighing on it. The distance between the two lines is the interesting part — not the direction of either one alone.
Covers the three US benchmarks, all sector ETFs, emerging markets and OMX 30. Single-stock coverage is deliberately limited to the Magnificent 7 (AAPL, MSFT, GOOGL, AMZN, META, NVDA, TSLA) so the window scan only runs on instruments with long, liquid history — scanning hundreds of individual names would produce data-mining noise rather than seasonality. Click the methodology toggle for the full calculation.
S&P 500 · intra-year path
1992–2025 average vs 2026Month by month
2026 overlay · average return · share of years positive · 34 years| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 2026 | +1.2% | -1.4% | -5.1% | +9.6% | +4.8% | -1.3% | +0.1% | +1.1% | +1.7% | — | — | — |
| Avg return | +0.2% | -0.7% | +0.6% | +1.4% | +0.5% | +0.2% | +0.9% | -0.3% | -0.7% | +1.3% | +1.9% | +0.9% |
| Positive | 62% | 53% | 65% | 68% | 62% | 50% | 62% | 56% | 56% | 65% | 68% | 74% |
Best windows · S&P 500
Exact calendar dates · 34 yearsAcross 34 completed years, S&P 500's strongest seasonal stretch runs from Sep 30 to Dec 31 (+4.7% on average, positive 82% of years). Other reliable windows are Mar 16 → Jun 16 (+3.3% avg, positive 79%) and Jun 24 → Jul 15 (+1.5% avg, positive 76%). The weakest stretch is Sep 16 → Oct 7 (-1.4% avg, positive 35%). The pattern is a historical calendar tendency, not a forecast — use it as context around position timing, not as a standalone signal.
What moves S&P 500 through the year
Jan–Mar. The year opens on flows, not fundamentals: pension and 401(k) contributions land in the first days of January, December's tax-loss selling reverses, and the beaten-up names from Q4 bounce hardest. Q4 earnings run mid-January to late February and reset full-year guidance — the highest-dispersion print of the year. Late February into March is the seasonal soft patch: guidance is already known, the buyback blackout is open again only partially, and the March quad-witching plus S&P rebalance adds mechanical volume without direction.
Apr–Jun. April is historically one of the two strongest months: Q1 earnings arrive against low expectations, and US tax receipts around April 15 have repeatedly coincided with a liquidity pocket. From May the base rate flattens — "sell in May" is real but uneven, and it is a volume story, not a calendar law: fewer participants means macro events (FOMC, payrolls, elections) move the tape further than they otherwise would. June ends with a quad-witching and Russell reconstitution that can distort the last week badly.
Jul–Sep. July usually starts strong on Q2 earnings and buyback windows reopening, then thins out through August as desks empty. September is the single weakest month in the record — mutual-fund fiscal year-ends (Oct 31) start forcing loss realisation, corporates enter blackout ahead of Q3 reporting, and the pre-announcement window for negative guidance is open. Most of September's damage is concentrated in the second half of the month.
Oct–Dec. The strongest stretch of the year, and the most mechanical. Q3 earnings clear the guidance risk, buyback authorisations resume at scale in late October and November, fund fiscal year-ends are past, and index-tracking flows plus December rebalances add persistent demand. November has the highest hit rate of any month; December's gain is concentrated in the final two weeks once tax-loss selling is finished.
Why seasonality matters. A seasonal pattern is never the cause — it is the residue of drivers that repeat: buyback windows opening and closing, tax-loss selling and its January reversal, fund fiscal year-ends, dividend and reinvestment dates, earnings calendars, restocking and build seasons. The average path only repeats in a given year if those same drivers actually show up. When the buyback window is open, revisions are rising and flows are positive, the seasonal tailwind tends to land. When the driver is absent or reversed, the pattern fails — and the failure itself is information.
How to read the chart. The grey line is the typical year. The green line is now. When this year runs above the grey path, the tape is stronger than its own base rate; when it runs below, something idiosyncratic is weighing on it. The distance between the two lines is the interesting part — not the direction of either one alone.
How we use it. As context, never as a signal. Read the window, then verify its driver is present this year; a tailwind with a live driver is worth waiting for, a tailwind without one is a coin flip. Price trend and the fundamentals still decide what you own — seasonality only decides how patient you should be about the entry.