Index Funds and Time in the Market
An index fund just buys the whole market instead of betting on which piece of it wins. Try to time it by dodging the worst days below, and discover you can't do that without also missing the best ones.
Worth reading first: The Math That Rewards Starting Early
Trying to dodge the market's worst days sounds like an obviously good idea. The problem is that nobody — not professional fund managers, not anyone — can reliably spot the worst days in advance, and the toggle below shows exactly what trying costs when it goes wrong.
An index fund just buys the whole market
An index funddoesn't try to pick winning companies — it simply buys all of them, in proportion to a benchmark like the S&P 500, and holds them. There's no manager guessing which stock outperforms; the fund's return is just whatever the whole market did, minus a very small fee.
Time in the market beats timing the market
“Timing the market” means trying to buy right before it rises and sell right before it falls. It requires being right twice, repeatedly, for years — and the market's biggest single days routinely arrive during the most volatile stretches, often within days of the worst ones, which is exactly when a nervous investor is most likely to have already stepped out.
Stayed invested every day
$26,045
Missed the 10 best days
$19,535
10 days out of 2520 trading days — a tiny fraction of the whole period — account for the entire gap between these two numbers.
Missing the ten best days changes everything
Toggle between the two paths above. Ten trading days, out of thousands across a decade — a tiny fraction of the whole period — account for the entire gap between them. Nobody rings a bell on the best days in advance; the only way to guarantee you're invested on all of them is to stay invested on all of the days.
Key takeaways
- An index fund buys the entire market in proportion to a benchmark, rather than trying to pick individual winners.
- Timing the market requires being right about both an exit and a re-entry, repeatedly, which nobody has reliably managed over long periods.
- The market's best days cluster near its most volatile stretches — often within days of the worst ones — which is precisely when a nervous investor is likely to be out.
- Missing just the ten best trading days across a decade changes the ending balance dramatically, even though those days are a tiny fraction of the total.