Crypto in a portfolio: which criteria count

There is no generally valid figure for the right crypto share, and this text does not name one of its own. What exists are criteria that have to be settled before any percentage, published figures on price swings and correlation, and a single rule of thumb that a consumer protection body has put in writing.

Why no percentage appears here

A quota can only be derived from a person's circumstances, not from the market. The joint warning issued by ESMA, EBA and EIOPA, the three European supervisory authorities, on 17 March 2022 therefore asks questions instead of giving numbers. The first is this: can you afford to lose all the money you put in? The same warning records that many crypto-assets are highly risky and speculative, and that consumers face the very real possibility of losing all the money they invest.

At the time of that warning the three authorities counted more than 17,000 different crypto-assets, of which Bitcoin and Ether together made up around 60 per cent of market capitalisation. The authorities name seven areas of risk, among them extreme price movements, misleading advertising, absent protection, product complexity, fraud, market manipulation and attacks on trading venues or wallets. Anyone looking for a percentage is looking in the wrong place. The first question is whether there is any money at all whose loss would be without consequence.

Three criteria before any figure

First the reserve. A German consumer advice centre names a buffer of two to three monthly salaries for unexpected costs, to be held in an account you can reach at any time. As long as that buffer is missing or a loan at a higher rate of interest is running, the question of a share does not arise at all.

Second the time horizon. What matters is not how long you intend to invest, but when you will definitely need the money. Anyone facing a deposit, a purchase or a tax payment in two years cannot put that amount into an asset whose price, according to the European supervisory authorities, can fall and rise quickly over short periods.

Third the capacity to bear losses, kept separate from the willingness to bear them. Willingness is a question of nerves, capacity a question of the household budget: what happens in concrete terms if the amount goes to zero? Work that through with your real figure, not in your head. The portfolio mixer shows how different shares affect a total holding.

Three starting positions and what separates them

The table below assigns the criteria to three typical positions. It contains no recommendation from us; the only range in it is marked as a rule of thumb and comes from the source named.

Why spreading within crypto is not spreading

A widespread error holds that several coins are more broadly spread than one. ESMA calculated the return correlations of the six largest crypto-assets excluding stablecoins for January 2021 to December 2023 and arrives at values between 0.46 and 0.82; the highest is the value between Bitcoin and Ether at 0.82. Translated, that means these assets move largely together, and investors barely distinguish between them.

The market itself is concentrated as well. Bitcoin, Ether and the stablecoin Tether stood for 74 per cent of total market capitalisation in December 2023, and the ten largest assets for 86 per cent. The link to the stock market is there too: the correlation between Bitcoin and the S&P 500 rose above 0.6 in the downturn of 2022, measured as a 90 day return correlation. With the gold price, by contrast, ESMA finds no clear connection, and the European Central Bank writes in its analysis of May 2025 that Bitcoin historically shows almost no correlation with gold but runs closely with risky assets and technology shares. Anyone planning crypto as a counterweight to equities is planning with a property that these measurements do not support.

What the figures say about practice

The European Central Bank examined selected euro area countries for its consumer expectations survey in November 2024. There, 9.7 per cent of respondents said that they or someone in their household held crypto-assets. The amounts are mostly small: among holders, 54 per cent named holdings below 1,000 euro and 91 per cent below 20,000 euro. Extrapolated, households held at least 75 billion euro, which corresponds to about 0.23 per cent of their financial assets and around 3 per cent of total crypto market capitalisation. These figures apply to the countries surveyed, not to the whole euro area.

For Germany, BaFin, the German financial supervisory authority, published its own survey in August 2026. According to it, around 13 per cent of adults hold crypto-assets, more than nine million people. The sample was 1,000 people answering 16 knowledge questions. Across all respondents, 36 per cent of the answers were correct and 19 per cent wrong, and for 45 per cent the respondents said they did not know the answer. Those who held crypto-assets themselves answered 57 per cent of the questions correctly and 31 per cent wrongly; the remaining 12 per cent fall arithmetically to the answer that they did not know. Put differently, holders could not answer, or could not answer correctly, close to half of the 16 questions. One finding stands out: 54 per cent of holders assumed that Bitcoin protects against inflation.

The only rule of thumb with a source

If a figure is to be named, then this one, and with its full label. The consumer advice centre of North Rhine-Westphalia (Verbraucherzentrale NRW) writes in its article of 22 October 2024 that anyone who wants to buy despite the risks should do so only as an addition of at most 5 per cent of their assets. The same source places Bitcoin expressly outside strategic investing and in the category of speculation, and points out that the money put in can be lost completely.

Those 5 per cent are the rule of thumb of a consumer protection organisation. They are not a statutory limit, not a supervisory requirement and not the result of an optimisation calculation, and they are not our own view. It is an upper limit, not a target: zero per cent lies within it as well. And it refers to assets, not to monthly income, which with small assets produces a very small amount. As an example: with assets of 20,000 euro that would be at most 1,000 euro, and with 5,000 euro at most 250 euro.

How to check your share and hold it

Fix the share before you buy, in writing and in euro, not only in per cent. After that, a share you once fixed does not stay there by itself. If the price rises, the share grows without you doing anything; if it falls, the share shrinks. So decide in advance at what deviation you reset, for instance at a doubling of the share, and stick to it. Bear in mind that a sale made to reset the share is a disposal for tax purposes; the German periods that then apply are set out in the article on the taxation of crypto-assets in Germany.

Work through these five points before buying. Is the buffer of two to three monthly salaries sitting in an account you can reach? Are loans at a higher rate of interest paid off? Do you know when you will definitely need the money, and is that date far enough away? Does your household stay stable if the amount falls to zero? And do you have a rule for resetting before the first jump in price arrives? How a share builds up over many instalments is covered in the article on the crypto savings plan; the published price swings are set out in the article on the volatility of Bitcoin.

Frequently asked questions

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