Concentration Risk arises when portfolio risk depends disproportionately on a limited number of positions, issuers, sectors, strategies, managers or common market factors. The relevant concentration is therefore not determined only by the number of holdings or by nominal allocation weights. Positions that appear different may respond to the same economic drivers and create a substantial common exposure.
For an individual hedge fund, concentration analysis should consider the composition of the underlying portfolio, including large positions, sector and geographic exposures, issuer concentrations and material factor sensitivities. Depending on the strategy, leverage and derivatives may also increase the economic importance of an exposure without producing an equally large cash allocation. A portfolio containing many securities can therefore remain highly concentrated if those securities share similar market, credit or volatility characteristics.
For a fund of hedge funds or other multi-manager portfolio, concentration risk also arises at the manager and strategy levels. Allocating capital across several managers does not necessarily provide diversification when the managers maintain similar directional exposures, trade related instruments or depend on the same market factors. Strategy classifications alone are consequently insufficient for measuring concentration.
Correlation analysis is important because concentration may develop across positions that are classified differently. Pairwise correlations, however, should not be considered in isolation. Correlations are estimated from historical data and may change materially under stressed market conditions. Factor analysis and stress testing can therefore provide additional information by identifying common economic exposures that may not be apparent from allocation categories or historical correlations alone.
Concentration limits based solely on allocation percentages can consequently provide an incomplete measure of risk. A 20% allocation to each of five strategies, for example, does not imply a well-diversified portfolio if several strategies have substantial exposure to the same equity, credit, interest-rate or volatility factor.
Due diligence should assess both explicit concentrations and less visible common exposures. Relevant analysis may include position and issuer concentrations, manager and strategy allocations, factor sensitivities, correlations, liquidity characteristics and stress-test results. The objective is to determine whether apparently diversified holdings are economically dependent on the same sources of return and risk, and whether losses could become concentrated under adverse market conditions.