How much bitcoin?
Fifteen tested claims on this site say almost nothing tells you when to buy. This page asks the question that survives — how much to hold — and lets you answer it yourself. Move the weight and everything below recomputes from the published monthly series.
A 20% bitcoin weight added 12.2 points of annual return to a portfolio started in 2015, and 4.8 points to one started in 2023. The extra drawdown it cost barely changed.
Growth of one unit, log scale. The chosen mix against the same portfolio with no bitcoin.
What the weight bought, and what it cost
Each point is an entry year. Further right means the bitcoin weight deepened the worst fall; higher means it added more annual return. The two do not move together, and that is the finding.
| Entered | No bitcoin | With bitcoin | Added | Extra drawdown |
|---|
Is it still a diversifier?
Rolling 36-month correlation of bitcoin to equities and to gold.
A weight that moves with the assets it is meant to diversify does less work than the aggregate figures suggest. This is the number most likely to change the answer above, and it is not stable.
The published ladder
134 monthly observations, 2015-07 to 2026-08. Base is 60% equities and 40% gold; the bitcoin weight is funded from both in proportion. Risk-free rate assumed at 2.0% a year.
| Bitcoin | Return a year | Volatility | Sharpe | Sortino | Worst fall | Longest underwater |
|---|---|---|---|---|---|---|
| none | 13.1% | 9.2% | 1.18 | 1.93 | -15.6% | 19 mo |
| 1% | 13.7% | 9.3% | 1.23 | 2.00 | -16.3% | 19 mo |
| 2% | 14.3% | 9.4% | 1.27 | 2.06 | -17.0% | 23 mo |
| 5% | 16.2% | 10.1% | 1.35 | 2.22 | -19.2% | 24 mo |
| 10% | 19.3% | 11.9% | 1.38 | 2.40 | -22.7% | 24 mo |
| 20% | 25.3% | 16.9% | 1.32 | 2.53 | -29.3% | 25 mo |
- No optimiser, no recommended weight. Optimising on 134 monthly observations produces answers that swing wildly on small changes in assumed return.
- Sharpe and Sortino — both shown because they disagree. Sortino penalises only downside deviation, which flatters an asset whose big moves are mostly upward.
- Longest underwater — consecutive months below a previous peak. This is what makes people sell.
What this does not show
Bitcoin went from about $300 to about $80,000 inside this sample. Every weight looks good in aggregate for that reason alone. The entry-year table exists because the aggregate hides how unevenly that arrived.
Every series is a monthly average, not a month-end close. It has to be: the equity and gold series in the data are monthly averages and there is no daily gold series. Averaging smooths, so volatility and the worst fall are understated — for every asset alike, which keeps the comparison fair.
The equity series is a price index, so it excludes dividends, roughly a point and a half a year. The base is understated and every bitcoin weight is flattered equally. There is no bond series, so the base is equities and gold rather than the usual 60/40.
This is not advice, and cannot be
These are historical distributions from a short, exceptional sample. 134 monthly observations is about one and a half bitcoin cycles.
They know nothing about your horizon, your tax position, your other assets, or what you would actually do in a thirty per cent drawdown — which is the variable that decides most outcomes.
Recomputed daily by fetch/portfolio.py and published as portfolio.json. The tool above recomputes in your browser from the same monthly series, so it cannot disagree with the ladder. Method on the methods page; the claims that motivated this page are on the scorecard.