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If you own shares in Interserve Plc (LON:IRV) then it’s worth thinking about how it contributes to the volatility of your portfolio, overall. In finance, Beta is a measure of volatility. Modern finance theory considers volatility to be a measure of risk, and there are two main types of price volatility. First, we have company specific volatility, which is the price gyrations of an individual stock. Holding at least 8 stocks can reduce this kind of risk across a portfolio. The second sort is caused by the natural volatility of markets, overall. For example, certain macroeconomic events will impact (virtually) all stocks on the market.
Some stocks mimic the volatility of the market quite closely, while others demonstrate muted, exagerrated or uncorrelated price movements. Beta is a widely used metric to measure a stock’s exposure to market risk (volatility). Before we go on, it’s worth noting that Warren Buffett pointed out in his 2014 letter to shareholders that ‘volatility is far from synonymous with risk.’ Having said that, beta can still be rather useful. The first thing to understand about beta is that the beta of the overall market is one. A stock with a beta below one is either less volatile than the market, or more volatile but not corellated with the overall market. In comparison a stock with a beta of over one tends to be move in a similar direction to the market in the long term, but with greater changes in price.
Check out our latest analysis for Interserve
What IRV’s beta value tells investors
Zooming in on Interserve, we see it has a five year beta of 1.76. This is above 1, so historically its share price has been influenced by the broader volatility of the stock market the market. If the past is any guide, we would expect that Interserve shares will rise quicker than the markets in times of optimism, but fall faster in times of pessimism. Many would argue that beta is useful in position sizing, but fundamental metrics such as revenue and earnings are more important overall. You can see Interserve’s revenue and earnings in the image below.
Does IRV’s size influence the expected beta?
With a market capitalisation of UK£15m, Interserve is a very small company by global standards. It is quite likely to be unknown to most investors. It has a relatively high beta, suggesting it is fairly actively traded for a company of its size. Because it takes less capital to move the share price of a small company like this, when a stock this size is actively traded it is quite often more sensitive to market volatility than similar large companies.