A plan only works if you keep it through the bad years.
Stay the course.
January 2005. €12,000 in twelve chips. Leave them where they are, or chase last year’s best performer.
Leaving it alone beat moving to last year’s best performer.
← Red LinesRed Line 45 of 48 The idea The numbers Where you see it Where it bends This game’s numbersHow strong the proof isBGood proof, with limits Where it comes from
Every long-term plan meets years when it looks broken. The plan only pays off for those still holding it when the good years come back.
A fund falls from 100 to 60 in a year and a half, is back at 100 after four years and at 130 after six. Sell near the bottom and you keep 60; hold and you have 130.
After the 2008 crash, world shares took several years to recover, then went on to new highs. Those who sold in 2009 missed the climb back.
Staying the course on a broken plan is stubbornness, not patience. Fix the plan in a calm week.
Yahoo Finance, historical pricesdigrin, monthly price history (second check)
Fund investors who jump in and out earn less than the funds they own, year after year in the data, though the gap is smaller in some kinds of fund.
- Mind the Gap 2026 Jeffrey Ptak, Morningstar, 2026
- Mutual fund flows and investor returns: An empirical examination of fund investor timing ability Geoffrey C. Friesen & Travis R. A. Sapp, Journal of Banking & Finance 31(9), 2796-2816, 2007
Checked 2 Nov 2026 · How we grade
- A Strong proof: Many good studies or long official data, from different teams or countries, point the same way.
- B Good proof, with limits: Solid studies agree on the direction, but the size varies, or the data covers few places or few kinds of people.
- C Mixed proof: Some good studies for, some against, or the evidence covers only part of the line.
- D Thin proof: Mostly one book’s argument, one survey or stories. It may be wise, but it has not been tested well.
- = True by the sums: It follows from arithmetic, so no study can overturn it. We still show what real data says.
John C. Bogle, Common Sense on Mutual Funds (1999). In our words, not quoted.
See it in numbers: Best days · Checking (From Zero)
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