Market risk and specific risk are two different forms of risk that affect assets. All investment assets can be separated by two categories: systematic risk and unsystematic risk. Market risk, or systematic risk, affects a large number of asset classes, whereas specific risk, or unsystematic risk, only affects an industry or particular company.
Systematic risk is the risk of losing investments due to factors, such as political risk and macroeconomic risk, that affect the performance of the overall market. Market risk is also known as volatility and can be measured using beta. Beta is a measure of an investment's systematic risk relative to the overall market.
Market risk cannot be mitigated through portfolio diversification. However, an investor can hedge against systematic risk. A hedge is an offsetting investment used to reduce the risk in an asset. For example, suppose an investor fears a global recession affecting the economy over the next six months due to weakness in gross domestic product growth. The investor is long multiple stocks and can mitigate some of the market risk by buying put options in the market.
Specific risk, or diversifiable risk, is the risk of losing an investment due to company or industry-specific hazard. Unlike systematic risk, an investor can only mitigate against unsystematic risk through diversification. An investor uses diversification to manage risk by investing in a variety of assets. He can use the beta of each stock to create a diversified portfolio.
For example, suppose an investor has a portfolio of oil stocks with a beta of 2. Since the market's beta is always 1, the portfolio is theoretically 100% more volatile than the market. Therefore, if the market has a 1% move up or down, the portfolio will move up or down 2%. There is risk associated with the whole sector due to the increase in supply of oil in the Middle East, which has caused oil to fall in price over the past few months. If the trend continues, the portfolio will experience a significant drop in value. However, the investor can diversify this risk since it is industry-specific.
The investor can use diversification and allocate his fund into different sectors that are negatively correlated with the oil sector to mitigate the risk. For example, the airlines and casino gaming sectors are good assets to invest in for a portfolio that is highly exposed to the oil sector. Generally, as the value of the oil sector falls, the values of the airlines and casino gaming sectors rise, and vice versa. Since airline and casino gaming stocks are negatively correlated and have negative betas in relation to the oil sector, the investor reduces the risks that affect his portfolio of oil stocks.