Learn the stock market › Saving for the long term › Lesson 4 of 5

How long should you stay invested?

Short answerThe longer you hold, the less often the market has lost money. Of every one-year period in the S&P 500 since 1928, 30% ended lower than they began. Over ten years it was 11%, over twenty years 3%, and no thirty-year period ended lower. But the worst case stayed bad for a long time: someone who bought in August 1929 had $48 left of every $100 twenty years later, without dividends.

Every start month since 1928

We start at every month's end since January 1928 and read the value the same month a set number of years later. The table shows how often the period ended lower, and what $100 became in the worst and in the median period.

Holding period	Ended lower	Worst: $100 became	Median: $100 became
1 year	30.4%	$30	$110
2 years	23.2%	$18	$117
3 years	21.0%	$16	$126
5 years	19.7%	$29	$147
10 years	11.2%	$35	$206
15 years	3.5%	$40	$278
20 years	3.4%	$48	$395
25 years	0.1%	$94	$561
30 years	0.0%	$188	$840

Over one year the range was wide. Someone who bought in June 1931 had $30 left of every $100 a year later, and 30% of all one-year periods ended lower, the latest one starting in March 2022. One or two years tell you little about what you will get.

When did it get safer?

Between five and fifteen years the share of losses fell clearly. The last ten-year period that ended lower began in January 2001. At the median, $100 became $206 over ten years.

Over fifteen years the last period that ended lower began in February 1931, around the 1929 crash. The last twenty-year period that ended lower began in August 1930. Over twenty-five years 1 period ended lower, the one from August 1929, and none of the 826 thirty-year periods did.

What the table doesn't say

Past years promise nothing about the next period, and the numbers are for one country. They are also for an index of 500 companies. A single company can fall and never come back.

The numbers apply to money that stays in for the whole period. If you need the money in two years, the market may be lower just then. How deep and how long the big falls went is in the study of every stock market crash since 1928, and the same periods as a rate per year are in the study of the stock market's average return.

If you invest every month rather than all at once, the outcomes look different. You can try that in the dollar cost averaging calculator.

Test yourself

What share of all ten-year periods in the S&P 500 since 1928 ended lower than they began, without dividends?

How we calculated

S&P 500 closes, the last of each month, from January 1928 to Nov 6, 2026. The month in progress is not counted.
Dividends are not included. With them fewer periods would have ended lower.
Inflation is not taken out. What it looks like after inflation is in Inflation and your savings.
The S&P 500 index started in 1957. The numbers before that come from its 90-company predecessor.
The periods overlap, so 1,174 one-year periods are not as many independent outcomes.