Portfolio Management: Risk and Mitigation

Modern Portfolio Theory(MPT) assumes that investors are risk averse, meaning that given two portfolios that offer the same expected return, investors will prefer the less risky one. Thus, an investor will take on increased risk only if compensated by higher expected returns. Conversely, an investor who wants higher expected returns must accept more risk. The exact trade-off will be the same for all investors, but different investors will evaluate the trade-off differently based on individual risk aversion characteristics. The implication is that a rational investor will not invest in a portfolio if a second portfolio exists with a more favorable risk-expected return profile – i.e., if for that level of risk an alternative portfolio exists which has better expected returns.

An investor can reduce portfolio risk simply by holding combinations of instruments which are not perfectly positively correlated. In other words, investors can reduce their exposure to individual asset risk by holding a diversified portfolio of assets. Diversification may allow for the same portfolio expected return with reduced risk. Diversification is one of two general techniques for reducing investment risk. The other is hedging. Diversification relies on the lack of a tight positive relationship among the assets’ returns, and works even when correlations are near zero or somewhat positive. It is important to remember that diversification only works because investment in each individual asset is reduced. If someone starts with $10,000 in one stock and then puts $10,000 in another stock, they would have more risk, not less. Diversification would require the sale of $5,000 of the first stock to be put into the second. There would then be less risk. Hedging, by contrast, reduces risk without selling any of the original position. The risk reduction from diversification does not mean anyone else has to take more risk. If person A owns $10,000 of one stock and person B owns $10,000 of another, both A and B will reduce their risk if they exchange $5,000 of the two stocks, so each now has a more diversified portfolio