A market-cap-weighted crypto basket can look diversified while carrying a very large position in one asset. That is not a flaw in the arithmetic. It is the arithmetic working exactly as designed.
A live snapshot of ten widely followed crypto assets shows the issue clearly. Bitcoin represents about 73.2% of the basket by market capitalization. Bitcoin and Ethereum together represent about 87.2%. The other eight assets share the remaining 12.8%.
This may be a reasonable description of the market. It is not automatically a reasonable portfolio. The difference matters for anyone building an index, setting a mandate, or explaining risk to an investment committee.
Methodology makes the weighting choice visible
The market snapshot for this analysis covers BTC, ETH, SOL, XRP, BNB, DOGE, ADA, AVAX, LINK, and SUI. Prices, daily percentage changes, and market capitalizations were pulled from a live finance quote feed between 02:23:43 and 02:25:07 UTC on August 27, 2026. The combined market capitalization was about $2.15 trillion at the feed timestamp of 02:25:09 UTC.
The calculation uses one plain rule: each asset’s weight equals its market capitalization divided by the combined market capitalization of the basket. The resulting weights are not a forecast and do not measure quality. They simply describe the relative size of the assets in the selected universe.
Index providers add further rules around eligibility, pricing, custody, liquidity, data quality, reconstitution, and rebalancing. The published MSCI Global Digital Assets Index Methodology and Nasdaq Crypto Index methodology show why a usable index requires more than a list of tickers. A portfolio designer should be able to state each rule before capital is allocated.
A market description is not a portfolio decision
Market-cap weighting has a strong advantage: it is transparent. It does not require an analyst to declare that one asset deserves a larger position because of a subjective view. It also tends to give more weight to assets with deeper markets and greater investable scale, although market capitalization alone is not a complete liquidity test.
The trade-off is concentration. The largest asset absorbs most of the basket’s weight. If the objective is to represent the market, that may be the point. If the objective is to spread risk across networks, applications, or economic roles, the same construction may fall short.
The distinction is especially important in crypto because asset labels can overstate diversification. Holding ten tokens does not create ten independent risk exposures. Large assets can respond to the same macroeconomic conditions, the same liquidity cycle, or the same broad risk sentiment. Two different networks can also share dependencies through stablecoins, exchanges, custodians, cloud infrastructure, bridges, or common market makers.
A portfolio therefore needs two descriptions. The first is the exposure map: how much capital is assigned to each asset. The second is the dependency map: which risks can affect several holdings at the same time.
The current basket is dominated by two assets
The snapshot gives Bitcoin a market capitalization of about $1.57 trillion and Ethereum about $301.4 billion. Their combined value is about $1.87 trillion, or roughly 87.2% of the ten-asset basket.
The next largest positions are BNB at about 4.5%, XRP at about 4.0%, and Solana at about 2.7%. Dogecoin is about 0.7%, while Chainlink is about 0.4% and Cardano about 0.4%. Avalanche and Sui are each below 0.2% of the basket.
That distribution creates a useful diagnostic. A market-cap-weighted investor who says “I own ten assets” may be describing the number of lines on a holdings report, not the number of meaningful risk drivers. Most of the portfolio’s market exposure is still determined by Bitcoin and Ethereum.
This is not an argument that smaller assets should receive larger weights. It is an argument for naming the objective. A broad market index should be judged by how well it captures the market. A diversified risk portfolio should be judged by concentration, co-movement, liquidity, and drawdown behavior as well.
A worked example shows the effect of a cap rule
Consider a hypothetical $10 million portfolio that follows the live ten-asset basket without fees or trading costs.
Under pure market-cap weighting, the Bitcoin position would be about $7.32 million. Ethereum would be about $1.40 million. The combined Bitcoin and Ethereum position would be about $8.72 million. The remaining eight assets would share about $1.28 million.
Now apply a simple 50% cap to Bitcoin while leaving the other weights proportional. The excess Bitcoin weight is moved to the other nine assets in proportion to their original market capitalizations. The result is not a claim that 50% is the correct limit. It is a way to show what a concentration rule changes.
The steps are straightforward:
1. Start with Bitcoin at 50% rather than 73.2%.
2. Reduce the other nine assets’ relative shares so that their total remains 50%.
3. Keep the same eligible universe and the same price snapshot.
4. Rebalance back to the rule at the chosen schedule or when a breach threshold is reached.
Under this capped design, Bitcoin falls from about $7.32 million to $5 million. The amount redirected away from Bitcoin is about $2.32 million. Ethereum becomes about 26.1% of the total portfolio, or roughly $2.61 million, because the other nine assets are scaled proportionally to fill the remaining 50%. The smaller assets also receive more capital in dollar terms, but their relative order does not change.
The cap does not remove market risk. It changes the source of that risk. The portfolio becomes less dependent on Bitcoin’s single-asset outcome and more exposed to the behavior, liquidity, and operational risks of the other assets. That is a design choice, not a free improvement.
An analyst should also test alternative rules. A 40% cap creates more redistribution than a 50% cap. An equal-weight basket creates much more exposure to smaller assets and may be harder to trade. A square-root or volatility-aware scheme sits between those extremes but introduces additional estimation and turnover decisions. Every method should be evaluated against the objective it is meant to serve.
Rebalancing rules determine how the index behaves
A weighting rule is only half of an index design. The rebalancing rule determines how the portfolio responds when prices move, market capitalization changes, or an asset fails an eligibility test.
A calendar rebalance, such as quarterly or semiannual, is easy to explain and audit. It can allow a large position to drift above its intended cap between reviews. A threshold rebalance acts when a limit is breached by a defined amount. It may control concentration more tightly, but it can create more trading during volatile periods.
A practical rule set should answer at least five questions:
1. How often is the universe reviewed?
2. What happens when an asset falls below the liquidity or trading threshold?
3. Is a concentration cap tested at each review, continuously, or both?
4. Are additions and removals phased in to reduce turnover?
5. How are hard forks, airdrops, contract migrations, and market disruptions handled?
Published index methodologies treat these details as part of the product, not as footnotes. The S&P Digital Market Indices policies and index math illustrates the broader principle: the calculation must be repeatable, and the policy must specify how the index behaves when the market is not orderly.
What the data does and does not tell us
The data tells us that a simple ten-asset market-cap basket is highly concentrated in Bitcoin and Ethereum. It tells us that adding more tickers does not necessarily produce more independent exposure. It also provides a clear baseline against which an allocator can compare capped, equal-weighted, sector-based, or volatility-aware alternatives.
The data does not tell us which weighting scheme will perform best. It does not measure future returns, downside risk, correlation, liquidity under stress, custody quality, or the legal status of any asset. Market capitalization can also contain assets that are difficult to trade at the displayed price, so an index must apply liquidity and investability screens rather than treating every reported value as available capital.
The data also does not tell us that a regulatory change will improve a portfolio. On August 18, the SEC proposed Regulation Crypto Assets, including a proposed one-time exemption for offerings up to $5 million over four years and a proposed exemption for offerings up to $75 million in each 12-month period, with disclosure and reporting conditions. The proposal is not a final rule, and it does not remove the need for asset-level diligence. The details are in the SEC’s Regulation Crypto Assets proposal.
For portfolio construction, the important point is process. A rule proposal can change the opportunity set, but the portfolio still needs an eligibility policy, exposure limits, data controls, and a rebalancing plan.
Why this matters for institutional design
Institutional portfolios need a defensible link between objective and construction. If the objective is market representation, market-cap weighting may be the cleanest starting point. If the objective is risk diversification, the starting point may need caps, tiers, sector buckets, or a different measure of economic exposure.
The best design is not the one with the most assets. It is the one whose concentration, turnover, liquidity, and governance rules can be explained before the outcome is known. That makes it easier to monitor drift, challenge assumptions, and separate a bad process from a bad market result.
Presolt helps investors turn market data into an explicit research process. Explore the approach at Presolt.com.
Compliance disclaimer
This article is for informational and educational purposes only. It is not investment advice, a recommendation, an offer to sell, or a solicitation to buy any digital asset or financial product. Digital assets are volatile and may lose some or all of their value. Past performance is not indicative of future results. Index examples are hypothetical, exclude fees, taxes, slippage, custody costs, and other expenses, and do not represent the performance of any actual portfolio. Investors should conduct their own research and consult qualified legal, tax, and financial professionals before making decisions.