Will the S&P 500 Be Up in 10 Years? Every Rolling Window Since 1928
Enumerating all of history's holding windows — the base rates, the losing decades, and the one variable that predicted them.
The base rates, computed from every window since 1928
Using calendar-year total returns (dividends reinvested), we can enumerate every possible holding window in the record:
| Holding period | Windows | Negative windows | Worst window | Best window |
|---|---|---|---|---|
| 5 years | 95 | 11 (12%) | 1928–1932: −12.7%/yr | 1995–1999: +28.6%/yr |
| 10 years | 90 | 5 (6%) | 1929–1938: −1.7%/yr | 1949–1958: +20.1%/yr |
| 20 years | 80 | 0 (0%) | 1929–1948: +2.4%/yr | 1980–1999: +17.8%/yr |
Read that middle row carefully: out of 90 ten-year windows, only 5 ended with less money than you started (total-return basis). And the 20-year row is the famous one — zero negative windows in nearly a century of data.
Where the losing decades hide
The negative 10-year windows cluster in exactly two neighborhoods: entries at the 1929 peak (the worst: 1929–1938, −1.7% annualized) and entries at the 1999–2000 dot-com top. Both were top-percentile valuation moments. That is the honest caveat to the base rate: the odds above are unconditional, and today's CAPE of 40.7× sits at the 99th percentile of history — the neighborhood where the bad decades started.
Sequence matters less than people fear, valuation more
- A lump sum at a random moment since 1928 won over 10 years 94% of the time.
- Dollar-cost averaging through a bad decade (2000–2009) still ended positive — contributions bought the 2002 and 2009 lows.
- The dispersion is the real story: the same 10-year hold has returned anywhere from −1.7% to +20.1% annualized depending on the entry year. See the buy-year × sell-year matrix to look up any pair.
FAQ
Can you lose money in the S&P 500 over 10 years?
Historically yes but rarely: 5 of 90 ten-year windows since 1928 ended negative (total-return basis), all starting at the 1929 or 1999–2000 valuation peaks.
Has the S&P 500 ever lost money over 20 years?
No — every one of the 80 twenty-year windows since 1928 ended positive with dividends reinvested. The worst 20-year stretch still annualized +2.4%.
What are the odds the market is up over 5 years?
88% of the 95 five-year windows since 1928 ended positive.
Windows computed from /api/sp500/annual-tr.json (calendar-year total returns), refreshed each trading day.