The cost of missing the best days calculator

Why timing fails arithmetically.

Interactive: the cost of missing the best daysEasy

Amount invested $ Annualised return % Years Best days missed Average best-day return %

Fully invested: —
Having missed them: —
Cost: —
Share of the outcome: —
Annualised, having missed them: —
Why it happens: —

Ten days out of roughly five thousand — a fifth of one percent of the trading days — and on these defaults around 40% of the outcome is gone. The usual objection is fair: missing the worst days would help just as much. The answer is that both sets are only identifiable afterwards, and they are neighbours in time. Anyone out of the market for one is almost always out for the other.

The idea behind it

This calculator belongs to Behavioural Finance, where the mechanism it computes is explained step by step, with the formula, what each input means and where the simple model stops being right. Everything is computed in your browser; nothing you type is sent anywhere.

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The same in full — six points, and why each one matters

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