If you own shares in Speedcast International Limited (ASX:SDA) 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. The first category is company specific volatility. This can be dealt with by limiting your exposure to any particular stock. The second type is the broader market volatility, which you cannot diversify away, since it arises from macroeconomic factors which directly affects all the 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. Any stock with a beta of greater than one is considered more volatile than the market, while those with a beta below one are either less volatile or poorly correlated with the market.
Check out our latest analysis for Speedcast International
What we can learn from SDA's beta value
Looking at the last five years, Speedcast International has a beta of 0.81. The fact that this is well below 1 indicates that its share price movements haven't historically been very sensitive to overall market volatility. This means that -- if history is a guide -- buying the stock would reduce the impact of overall market volatility in many portfolios (depending on the beta of the portfolio, of course). 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 Speedcast International's revenue and earnings in the image below.
Could SDA's size cause it to be more volatile?
Speedcast International is a noticeably small company, with a market capitalisation of AU$411m. Most companies this size are not always actively traded. It is not unusual for very small companies to have a low beta value, especially if only low volumes of shares are traded. Even when they are traded more actively, the share price is often more susceptible to company specific developments than overall market volatility.