What is Concentration?
Concentration measures the proportional weight a single equity position holds within a portfolio. This metric assesses portfolio risk and guides diversification strategy.
Theoretical Foundation
Modern Portfolio Theory demonstrates that concentrated positions generate suboptimal risk-adjusted returns. Diversification reduces company-specific risk without proportionally sacrificing expected returns. Concentrated portfolios expose investors to idiosyncratic risk without adequate compensation.
Concentration Thresholds
5-10% Range (Yellow Flag)
Warrants monitoring or planned management. Common situations include:
- Strategic overweighting for high-conviction positions
- Employee stock compensation from ongoing grants or appreciation
- Positions with embedded capital gains creating tax friction
- Inherited holdings with emotional or estate planning considerations
15-20%+ Range (Red Flag)
Requires immediate strategic attention. Typical scenarios include:
- Founder or executive equity comprising significant net worth
- Stock option exercises or RSU vesting creating concentration spikes
- Appreciation significantly outpacing broader portfolio growth
- Corporate mandated holding requirements for officers and directors
- Restricted stock with lockup periods preventing liquidation
Risk Dimensions
Concentration analysis extends beyond simple percentage weighting:
- Correlation risk emerges when multiple positions in the same sector compound exposure
- Liquidity constraints from restricted stock, private equity, or illiquid securities limit exit options
- Tax basis considerations arise when low-cost-basis positions face significant capital gains upon sale
- Income dependency creates compounded risk when employment income and equity share the same source
- Volatility characteristics of high-beta or cyclical securities amplify concentration effects
Advisor Approaches
Risk assessment frameworks vary based on:
- Client risk capacity and sophistication
- Time horizon and liquidity requirements
- Tax implications and realization strategies
- Available hedging tools and implementation costs
- Behavioral considerations affecting investor decision-making
Application
Concentration percentage serves as the trigger for deeper analysis. Understanding whether concentration is growing through ongoing grants or appreciation, or can be reduced through expiring restrictions or systematic sales, determines the appropriate risk management approach.