History of Market · The Chronicle of the U.S. Stock Market S&P 500
Gathering I · leaf 21 of 27
S&P 500 · Monthly Heatmap

S&P 500 · Monthly Heatmap — Twelve Months of Seasonality

Monthly seasonality — Which months tend to rise or fall: a year-by-month return heatmap.

Monthly return colours since 2000. November and April carry the highest win rates; September has the longest history of negative months.

View the interactive chart Download raw JSON

What this page answers

Across a 27 year sample, the highest-probability month for the S&P 500 is November (positive +77% of the time) and the weakest is February (+48%). Seasonality is a statistical lean, not a trading guarantee — any single year can deviate wildly.

Monthly return colours since 2000. November and April carry the highest win rates; September has the longest history of negative months. The data is refreshed by the History of Market pipeline and published as a stable JSON endpoint for research, citation, and AI-agent use.

The plate

S&P 500 · Monthly Heatmap — Twelve Months of Seasonality123456789101112200020012002200320042005200620072008200920102011201220132014201520162017201820192020202120222023202420252026
Plate I.21 Monthly return colours since 2000. November and April carry the highest win rates; September has the longest history of negative months. 2026-09-03

Latest Snapshot

Updated
2026-09-03

S&P 500 — monthly win rates

S&P 500 — monthly win rates
MonthShare of positive months
January+52%
February+48%
March+59%
April+70%
May+74%
June+59%
July+67%
August+63%
September+48%
October+62%
November+77%
December+65%

Showing the full record (12 rows). Raw series: https://historyofmarket.com/api/sp500/monthly.json

Data & Source

GET /api/sp500/monthly.json — Canonical dataset endpoint.

Exchange closing prices · Company filings · Robert Shiller · FRED · NBER.

FAQ

Which month is historically strongest for the S&P 500?

November, positive in +77% of sampled years; the weakest is February (+48%).

Where does this data come from?

History of Market combines public market and macro datasets — exchange closing prices, company filings, Robert Shiller, FRED, NBER, and the UBS Global Investment Returns Yearbook (Dimson–Marsh–Staunton). The exact endpoint for this panel is linked below.

How often is it updated?

Daily-tier datasets refresh after the U.S. market close, with a broader weekly refresh on Sunday. The timestamp shown on this page comes from the JSON payload.

Can I use the data?

Yes, for research and education with attribution to History of Market. Upstream data sources retain their own terms.