In brief: Diversification spreads exposure across different risk drivers, while concentration risk occurs when too much portfolio value depends on one company, sector, or theme.
Diversification is about risk drivers
Owning multiple holdings does not automatically create a diversified portfolio. If those holdings depend on the same interest-rate environment, commodity price, customer, or technology trend, they may fall together.
Diversification works best when exposures are different enough to respond differently to economic and company-specific events.
Correlation and position size
Correlation describes how two assets have moved together historically. It can help identify overlapping exposures, but correlations are not fixed and can rise during market stress.
Position size determines how much one holding can affect the whole portfolio. Review individual positions, sectors, geographies, and factor exposures rather than counting tickers alone.
Avoiding false diversification
Several companies may appear different but share the same risk, such as high sensitivity to rates or dependence on one supply chain. Funds can also contain overlapping holdings with individual stocks.
A periodic holdings review can reveal concentration that is not obvious from the number of positions.
A practical review
- List the largest company, sector, and theme exposures.
- Check correlation and volatility alongside expected return.
- Stress-test the portfolio against rate, recession, and industry scenarios.
- Set review rules before a position becomes emotionally difficult to reduce.
Important: This guide is for general education and research. Market data, estimates, and technical signals can be incomplete or wrong. Nothing on this page is personal investment, tax, or financial advice.