Diversifiable and Non-diversifiable Risk
The Capital Asset Pricing Model introduced the concepts of diversifiable and non-diversifiable risk. Synonyms for diversifiable risk are idiosyncratic risk, unsystematic risk, and security-specific risk. Synonyms for non-diversifiable risk are systematic risk, beta risk and market risk.
If one buys all the stocks in the S&P 500 one is obviously exposed only to movements in that index. If one buys a single stock in the S&P 500, one is exposed both to index movements and movements in the stock based on its underlying company. The first risk is called “non-diversifiable,” because it exists however many S&P 500 stocks are bought. The second risk is called “diversifiable,” because it can be reduced it by diversifying among stocks.
Note that there is also the risk of overdiversifying to the point that your performance will suffer and you will end up paying mostly for fees.
The Capital Asset Pricing Model argues that investors should only be compensated for non-diversifiable risk. Other financial models allow for multiple sources of non-diversifiable risk, but also insist that diversifiable risk should not carry any extra expected return. Still other models do not accept this contention
Read more about this topic: Diversification (finance)
Famous quotes containing the word risk:
“Men’s hearts are cold. They are indifferent. Not all the coal that is dug warms the world. It remains indifferent to the lives of those who risk their life and health down in the blackness of the earth; who crawl through dark, choking crevices with only a bit of lamp on their caps to light their silent way; whose backs are bent with toil, whose very bones ache, whose happiness is sleep, and whose peace is death.”
—Mother Jones (1830–1930)