Single-Stock and Employer Concentration Risk

Concentration can occur across the whole household

An employee may receive salary, bonus, pension exposure and company shares from the same employer. If that company faces difficulty, income and investments can be hit together. Looking only at the brokerage account understates the concentration.

A successful holding can become a larger risk over time

If one share rises faster than the rest of the portfolio, its weight increases automatically. A position that began as modest can become dominant without any new purchase.

Diversification reduces company-specific risk, not all market risk

Spreading exposure across many issuers, sectors and regions can reduce the effect of one company's failure. It cannot prevent losses when broad markets fall.

Model tax and liquidity before changing a position

Selling a concentrated holding can create tax or contractual consequences depending on the jurisdiction and account. A staged plan may differ from an immediate sale. Educational modelling should show the trade-offs without assuming one universal tax treatment.

Quality check for concentration risk

Measure the holding as a share of investable assets and then consider whether employment income, bonuses or deferred compensation depend on the same company. Stress both the security value and the income source together. This exposes a risk that is easy to miss when the portfolio and career are assessed in separate worksheets.