Why Timing the Market Is Hard

Why this matters

After everything in this module, recessions, bear markets, bubbles, a natural thought is: why not simply step out before the bad times and back in before the good ones? It's the most tempting idea in investing. This lesson tests it against the data, and the results explain why most long-term investors don't try.

Two decisions, not one

To time the market successfully, you have to get out before a decline and get back in before the recovery. Getting only the first one right isn't enough: selling before a 30% fall is wasted if you buy back in after a 40% rebound. And both decisions have to be made in real time, usually amid alarming or exciting news.

The research recognized by the 2013 Nobel Prize in economics found that there is no way to predict stock and bond prices over the next few days or weeks, although the broad course over several years is somewhat more predictable.¹ Most timing decisions are about the short term, which is exactly where prediction is hardest.

Testing it on nearly a century of data

Using yearly S&P 500 returns, including dividends, and 3-month Treasury bill returns from Damodaran's data,² here's how some timing approaches compare with simply staying invested from 1929 to 2025:

Approach	Average yearly growth
Stay invested the whole time	9.7%
Move to Treasury bills for a year after every losing year	7.8%
Miss the 5 best years, in Treasury bills instead	7.7%
Miss the 10 best years, in Treasury bills instead	6.2%
Skip the 5 worst years, in Treasury bills instead	12.3%

Calculated for this lesson from yearly data, before fees and taxes. "Average yearly growth" is the compound rate. Yearly data can't capture moves within a year.

The table shows both sides honestly. Skipping the worst years would have been wonderful. But the simple, rule-based attempt to avoid trouble, stepping aside after a bad year, cost almost two percentage points a year, compounded over a lifetime. The reason is that good years tended to follow bad ones: five of the ten best years in this period, including 1933, 1954, 1958, and 1975, came right after a losing year.² Investors who stepped aside after the losses were out of the market for some of the biggest gains.

The rest of this lesson is for members

Still to come in this lesson: The evidence from real investors, What long-term investors do instead, the key takeaways, and 2 quiz questions with explanations.

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