Ask someone to list their biggest investment and they will name a stock, a fund, or a property they chose.
Ask them to list their biggest exposure and the answer is often something they never chose at all. It came with the employer, the city, the country, or the index.
Concentration is rarely a decision. It is an accumulation. Each step, a bonus paid in shares, a flat that went up, an index fund that was "diversified", looked reasonable. The sum is a portfolio whose fate rests on one thing.
Diversification is not the number of holdings. It is the number of things that have to go wrong at once.
Four markets, four recent examples as of early 2026. Same failure mode.
China: the house and the trust product
Residential property is reported to make up roughly 70% of urban Chinese household assets (a secondary figure we could not match to a statistical source, but the direction is not in dispute). Property then had a bad few years: new-home prices have fallen year on year for most of three years by most counts, Evergrande was delisted in August 2025, and Country Garden completed a US$17.7 billion offshore restructuring in December 2025.
The wealthier households had a second concentration that looked like diversification. Trust products sold through banks as quasi-deposits turned out to be credit risk. The Zhongzhi group, one of the largest sellers of such products, declared bankruptcy in January 2024. Roughly 150,000 high-net-worth investors are reported to be affected, claims must be filed formally, and recovery is likely to take years.
The household did not hold "a diversified portfolio of property and savings". It held one correlated bet on the credit of the property sector, in two wrappers.
Taiwan: one company, plus leverage
Taiwan's market is dominated by a handful of technology names. A holder of "the Taiwan market" is, to a large degree, a holder of the chip industry with some other things attached.
On 7 April 2025 the main index fell a record 9.7% after US tariff announcements, and Bloomberg reported that part of the move was the unwinding of leveraged bets. The government authorized a NT$500 billion stabilization fund.
Concentration is dangerous. Concentration financed with borrowed money is a different category. A drawdown stops being a paper loss and becomes a margin call, and the forced sale happens at the bottom.
The United States: a diversified index is not a diversified portfolio
The seven largest US companies reached about 34% of the S&P 500 in December 2025, up from about 12% in 2015, according to figures cited by CNBC.
A household might hold an S&P 500 fund, a technology fund, a 401(k) target-date fund and employer stock. They look like four things. Underneath, they overlap heavily.
Indonesia: when the index itself is the risk
In late January 2026, MSCI flagged weak shareholding transparency and low free float in Indonesian stocks and froze index changes for the market. The Jakarta Composite fell more than 11.5% in two days, wiping out roughly US$80 billion, with three trading halts. The head of the exchange and the head of the securities regulator both resigned.
An index fund tracks the index. When the index provider questions the market itself, passive investors are the ones forced to act. The risk is mechanical, not a judgment about any individual company.
The finance fundamentals
Risk adds up through correlation, not through count. Portfolio theory makes this precise. A portfolio's risk depends on weights, volatilities and correlations. Two assets that move together add risk almost as if they were one. Owning forty things that depend on the same factor is owning one thing.
Look through the wrapper. A fund or a trust is a container. Risk lives in what is inside. The right question about any holding is: what does it ultimately depend on?
Behavior builds concentration. Behavioral finance names the habits behind it: familiarity ("I know this company"), home bias, overconfidence, and anchoring on the price paid. Concentration feels like knowledge. It is the same position viewed from inside.
Single-position risk has its own playbook. The private wealth material covers concentrated holdings in detail: sell, hedge, diversify gradually, or hold on purpose with a limit. Tax and legal constraints, such as lock-ups and basis, usually decide the pace.
A look-through exercise you can do in an hour
List every holding, then ask the same five questions of each. Then total the answers in a table.
| Question | What you are looking for |
|---|---|
| Which country does it depend on? | Home bias, including property and salary |
| Which single names are inside it? | The same stock held by three funds |
| Which sector or theme drives it? | One technology cycle across four funds |
| Which currency is it earned and valued in? | See the currency you did not choose |
| Is it borrowed against? | Margin loans, mortgage, pledged shares |
Then add the human capital line: your salary, your employer, your industry. If the answers keep landing on the same cell, that is the position.
Practical implications
- Name your largest exposure out loud after the look-through. If you are surprised, that is the finding.
- Set a limit before the market sets one for you. An Investment Policy Statement can cap any single name, sector or country as a percentage of net worth. The cap is a decision made while calm.
- Treat leverage as a multiplier on concentration. A concentrated position with no debt can be held through a drawdown. With debt, it may not be.
- Reduce gradually and on a schedule if the position is large or tax-heavy. A rule such as "sell a fixed fraction each quarter" removes the need to pick a moment.
- Re-run the exercise annually. Concentration returns on its own. The best-performing asset becomes a larger share of the portfolio simply by working.
Update, October 2026: what the following months added
The same pattern showed up again, in the same markets and in a fifth.
- China. A Beijing court ordered the liquidation of the Zhongzhi group and more than 300 affiliates on 15 April 2026. Creditor claims had to be filed formally, with recovery expected over years.
- Taiwan. TSMC is reported to be more than 40% of the main index. On 17 July 2026 the index fell a record 2,953.71 points, or 6.47%, on an AI-stock sell-off and a TSMC margin warning. Brokerage accounts reached a reported 14.6 million, and brokerage loans were reported up 160% year on year in mid-2026.
- United States. Another aggregator puts the top ten stocks at 38% to 40% of the S&P 500 in mid-2026, and one bank estimate attributes about 46% of 2026 earnings growth in the index to the seven largest.
- Indonesia. MSCI extended its review to November 2026, with a possible consultation on reclassifying Indonesia from emerging to frontier.
- Singapore. The Straits Times Index set a record close of about 5,469 on 13 July 2026. The three local banks, DBS, UOB and OCBC, led it, and by one secondary count they make up more than half of the index. Nothing here is a warning about banks. The point is the arithmetic: a household that owns an STI fund, the bank shares directly, a home loan from one of those banks, and a salary from a company in the same ecosystem holds the same risk four times.
What we could not confirm
The body of this post reflects what was known on 3 February 2026; later developments are in the update section. Several market figures come from single secondary sources: the 70% property share, the share of the STI held by the three banks, the S&P concentration shares (which vary by method and date), and some Taiwan market statistics. Counts of consecutive months of Chinese price declines conflict between sources. Treat the numbers as illustrative of the pattern. This is education, not investment advice.
Sources
- CNN, Zhongzhi bankruptcy (5 January 2024); The Edge Malaysia on the April 2026 liquidation order
- NPR, Evergrande's delisting (25 August 2025); Kirkland & Ellis, Country Garden restructuring (January 2026)
- Taipei Times, record fall on 7 April 2025; Focus Taiwan, 17 July 2026 market close; Taiwan Business TOPICS, Taiwan's markets see a new generation of investors (September 2026)
- SIAS, STI record on 13 July 2026
- CNBC, Magnificent Seven share of the S&P 500 (12 December 2025)
- Tempo English, IHSG plunge explained; Indonesia Business Post, MSCI extends Indonesia review