What it means
Every share price moves for two broad reasons: something happened to the whole market, or something happened to that particular company. The first is market risk and cannot be diversified away, while the second is company risk and largely can be.
That distinction drives one of the most practical ideas in finance. If you own 40 companies across different industries, one firm's plant fire is a small dent in your portfolio, but if you own only that one firm it can be catastrophic.
For managers inside the business, company risk is not something to diversify away, it is something to manage. Customer concentration, single-supplier dependence, key-person exposure, litigation, product recalls and cyber incidents are all company risk, and the tools for handling them are insurance, contracts, redundancy in the supply chain and stronger controls rather than portfolio construction.
Company risk also explains why cost of capital is calculated the way it is. Standard asset pricing assumes investors hold diversified portfolios, so they are only paid for bearing market risk, and company-specific risk earns no extra expected return in a public market context.
The nuance is that private owners and undiversified founders do bear company risk in full. A family that has 90% of its wealth in one business genuinely carries specific risk, which is why private company valuations often include a company-specific risk premium that a listed company would not need.
In practice
Real-world examples.
Example
A specialist packaging supplier earns 45% of revenue from a single drinks brand. When that customer moves to a competitor at renewal, the supplier's profits halve even though its industry and the wider economy are growing.
Example
A listed restaurant group suffers a food safety incident at three sites and its shares fall 18% in a week while the sector index is flat. The move is almost entirely company risk, and analysts adjust their forecasts for that business alone.
Example
A software company's chief architect, who personally designed its core platform, leaves for a competitor. The board classifies this as key-person company risk and responds with documentation requirements, a retention pool and a deputy architect role rather than with any change to its market strategy.
Formula
Calculation
Total risk (variance) = systematic risk + company-specific risk, where systematic risk = beta squared x market variance.
Take a manufacturer whose share price has a total annual standard deviation (a measure of how widely returns swing) of 20%, giving a variance of 20 x 20 = 400. The company's beta is 1.2 and the market's standard deviation is 15%, giving a market variance of 15 x 15 = 225.
Systematic risk = 1.2 x 1.2 x 225 = 1.44 x 225 = 324.
Company-specific risk = 400 - 324 = 76.
Company-specific standard deviation = the square root of 76, which is about 8.7%.
So 76 / 400 = 19% of this company's total return variance comes from company-specific events, and that 19% is the portion a diversified investor can largely remove by holding other shares.Case study
Seen in the real world.
Larkspur Instruments is an illustrative, fictional maker of laboratory sensors that produced 70% of its output at a single leased plant. Its results were strong, its market growing, and its board spent most of its risk discussion on interest rates and demand cycles, which are market risks it could do little about.
A three week shutdown after a water main burst under the plant cost the fictional company roughly $2,400,000 in lost contribution and $600,000 in expedited freight, a $3,000,000 hit that had nothing to do with the economy. The board's review concluded that its biggest exposure was concentration in one building, one production line and two component suppliers.
Over the following year Larkspur qualified a second contract manufacturer, dual-sourced its two critical components and raised business interruption cover, at an ongoing cost of about $300,000 a year. Shareholders holding a diversified portfolio would not have paid extra for that protection, but the founding family, whose wealth sat almost entirely in the business, valued it highly, which is exactly the split between diversifiable and undiversifiable exposure.
Watch out
Common mistakes.
- Treating company risk and total risk as the same thing. Total risk includes market movements that affect every business, and separating the two is what tells you whether a share price fall is about the company or about the world.
- Expecting a higher return for taking company-specific risk in a listed portfolio. Because the risk can be diversified away at almost no cost, the market does not pay you to bear it, so concentration adds volatility without adding expected reward.
- Assuming diversification inside one industry is enough. Holding eight regional housebuilders removes very little company risk, because most of what drives them is a shared sector exposure rather than firm-specific events.
Questions
People also ask.
Is company risk the same as business risk?
They overlap heavily, though business risk usually refers to the operating uncertainty of the firm's activities while company risk is the broader term used in portfolio theory for everything that is specific to one entity.
Can a company reduce its own company risk?
Yes, through diversifying customers and suppliers, insurance, succession planning, stronger internal controls and avoiding single points of failure in operations.
Why do private company valuations often add a company-specific risk premium?
Because private owners and buyers are frequently undiversified, so they genuinely bear specific risk and demand a higher return to compensate for it.
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