Portfolio Lab research · 10 September 2026 · 4 min read
Bullish on Bitcoin? Test Conviction and Position Size Separately
You can have a strong Bitcoin thesis without giving every pound of your wealth the same job.
Conviction has a horizon. Spending has a date.
Someone who expects Bitcoin to compound at 30% a year may reasonably want substantial exposure. But a long-term return assumption does not tell them how to pay for a house deposit, a career break or next year’s living costs along the way.
That is the allocation question worth testing: how much exposure advances the plan while leaving room for the plan to happen on time? Holding less than 100% Bitcoin can be consistent with conviction. It can give the Bitcoin position time to work.
A stronger thesis changes the upside calculation
We started with 60% global shares, 30% US aggregate bonds and 10% cash, measured in USD. Each Bitcoin allocation is funded proportionally: 5% Bitcoin leaves 57% shares, 28.5% bonds and 9.5% cash. We tested annual compound Bitcoin return assumptions of 15% and 30%.
| Bitcoin weight | 15% BTC return assumption | 30% BTC return assumption | BTC −70%; others flat | Joint shock |
|---|---|---|---|---|
| 0% | 6.23% | 6.23% | 0.00% | -15.00% |
| 1% | 6.38% | 6.52% | -0.70% | -15.55% |
| 5% | 6.95% | 7.67% | -3.50% | -17.75% |
| 10% | 7.64% | 9.08% | -7.00% | -20.50% |
| 20% | 8.90% | 11.80% | -14.00% | -26.00% |
At 5% Bitcoin, moving the Bitcoin return assumption from 15% to 30% lifts the modelled portfolio return from 6.95% to 7.67% a year. At 20% Bitcoin, it moves from 8.90% to 11.80%. A more bullish assumption makes the allocation more consequential; it does not establish what someone should own.
Volatility is not the same thing as loss
Volatility describes variability, not permanent impairment. A price decline does not, by itself, settle a long-term investment thesis. Equally, recovery is not assured simply because a holding has fallen.
For a household, the practical issue is whether spending needs could force a sale before the thesis has time to play out. In the isolated shock, a 5% Bitcoin position contributes a 3.5% portfolio decline. On a $100,000 starting portfolio, that is a $3,500 mark-to-market fall. Whether it disrupts a plan depends on when the money is needed and what other resources are available.
The rest of the portfolio matters too. If Bitcoin falls 70%, shares fall 20% and bonds fall 10%, that same allocation falls 17.75%, or $17,750 per $100,000. Cash is flat in this illustration. Calling only the Bitcoin contribution “the portfolio risk” would miss most of this particular shock.
For someone working in Bitcoin, there is another question: could income weaken at the same time as investments? These calculations do not model employment income. They do give you a concrete starting point for deciding which upcoming commitments need funding outside the long-term position.
A useful next test is to vary the allocation and the return assumption independently. Then ask: if this price shock happened before my next major expense, could I still leave the long-term investment alone?
Test your own Bitcoin allocation →
What this comparison does and does not show
The top two return columns are annual compound portfolio estimates from Portfolio Lab’s return and covariance model, not a simple weighted average of compound asset returns. Bitcoin volatility stays at 42.5% and correlations stay fixed. Other asset assumptions use the app’s USD reference inputs at the snapshot date. Changing the Bitcoin return assumption does not change volatility or the separately specified shocks.
The shocks apply to starting weights before any rebalancing. They have no assigned probability and are neither a maximum drawdown estimate nor a simulated return path. Taxes, fees, inflation, currency changes and spending withdrawals are not included. The displayed 0 to 20% range is a comparison range, not proof that an optimum lies inside it. These are scenario illustrations, not promised returns or an allocation recommendation.
The live calculator can change as inputs are updated. This article and chart retain the dated snapshot. Download the calculation evidence, read how Bitcoin return assumptions are set, or explore Bitcoin conviction and financial goals.