THE MILLION MONKEY EXPERIMENT
What happens when one million monkeys pick stocks at random? Some of them will look like investment legends — and that is precisely the point.
The distribution
10,000 monkeys, identical rules, Jul 2016 – Jul 2026: $10,000 into ten random S&P 500 stocks, equal weight, buy & hold. The spread below is pure luck — no monkey knew anything.
| Percentile | Total Return | $10,000 became |
|---|---|---|
| Unluckiest 1% | +101.8% | $20,184 |
| Unluckiest 10% | +168.6% | $26,865 |
| Unluckiest 25% | +222.9% | $32,292 |
| Median monkey | +313.3% | $41,332 |
| Luckiest 25% | +470.2% | $57,020 |
| Luckiest 10% | +743.6% | $84,356 |
| Luckiest 1% | +1713.6% | $181,357 |
benchmark over the same window: S&P 500 +298.3% ($10,000 → $39,834)
Why do so many monkeys win?
Two honest reasons. First, equal-weighting ten random stocks behaves differently from the market-cap-weighted S&P 500 — random picks systematically tilt toward smaller index members. Second, our monkeys currently pick from today's S&P 500 constituents: companies that failed along the way are not in the draw. That is survivorship bias, it flatters every monkey, and it is exactly the effect this site exists to demonstrate. Real fund managers publish their track records with the same tailwind. Full methodology.
The lesson
When enough portfolios are generated at random, spectacular track records are guaranteed to exist — no skill required. The interesting question is not whether the best monkey is a genius. It is how you would tell a lucky monkey from a genius at all. (So far, nobody reliably can.)