Claim check: Time in the market beats timing
“Missing the best 10 days wrecks your returns, so time in the market beats timing the market.”
What the data says
Partly Partly: missing the best 10 days cost a median 36% of the total growth across 5 markets (0 at or above the one-third mark in both halves), and 60% of those best days fell within 21 trading days of one of the worst days. The direction mostly points the claimed way, but not strongly enough to be sure.
It holds in some markets or periods, leans the right way without proof, or helps on risk but not on return.
Who says it
Fund companies (JPMorgan, Fidelity) chart this in every retirement brochure.
Origins are as commonly cited and were not independently verified.
How we tested it
For each market with positive growth we replace the 10 best daily returns with zero (cash) and measure how much of the total log growth disappears; then the same for the 10 worst days, and for both. 'Wrecked' means at least a third of the total growth is lost, and in each half of the history the best 5 days must cost at least that share. We also count how many of the best days fall within 21 trading days of one of the worst days.
Results
| Market | CAGR | Miss best 5 | Miss best 10 | Miss best 20 | Miss worst 10 | Miss both 10 | Growth lost | Best near worst |
|---|---|---|---|---|---|---|---|---|
| S&P 500 | +13.8% | +11.2% | +9.6% | +7.1% | +18.6% | +14.1% | 29% | 80% |
| Gold | +7.5% | +5.9% | +4.7% | +2.5% | +11.5% | +8.7% | 36% | 20% |
| Silver | +6.1% | +3.4% | +1.2% | -2.8% | +16.0% | +10.7% | 80% | 70% |
| Bitcoin | +52.0% | +40.4% | +31.9% | +18.9% | +81.1% | +57.3% | 34% | 30% |
| Ether | +22.9% | +9.2% | -0.6% | -15.6% | +60.8% | +30.1% | 103% | 60% |
CAGR if the best or worst days are missed (S&P 500)
Stability across the two halves of history
A saying that only works in one half of the history is not much of a rule. Each row shows the effect in the full history, the first half and the second half; green means the claimed effect was present.
| Market | Full history (best 10) | First half (best 5) | Second half (best 5) |
|---|---|---|---|
| S&P 500 | 29% | 20% | 34% |
| Gold | 36% | 184% | 21% |
| Silver | 80% | — | 39% |
| Bitcoin | 34% | 30% | 35% |
| Ether | 103% | 55% | — |
The honest caveat
The exercise is hypothetical (nobody can pick those days) and it also shows missing the worst days helps just as much.
Descriptive statistics from historical data, before costs. Not a forecast and not investment advice.
Questions
Missing the best 10 days wrecks your returns, so time in the market beats timing the market.
Partly: missing the best 10 days cost a median 36% of the total growth across 5 markets (0 at or above the one-third mark in both halves), and 60% of those best days fell within 21 trading days of one of the worst days. The direction mostly points the claimed way, but not strongly enough to be sure.
How was this claim tested?
For each market with positive growth we replace the 10 best daily returns with zero (cash) and measure how much of the total log growth disappears; then the same for the 10 worst days, and for both. 'Wrecked' means at least a third of the total growth is lost, and in each half of the history the best 5 days must cost at least that share. We also count how many of the best days fall within 21 trading days of one of the worst days.