Anyone researching Luby's, Inc. (NYSE:LUB) might want to consider the historical volatility of the share price. Volatility is considered to be a measure of risk in modern finance theory. Investors may think of volatility as falling into two main categories. The first type is company specific volatility. Investors use diversification across uncorrelated stocks to reduce this kind of price volatility across the 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 see their prices move in concert with the market. Others tend towards stronger, gentler or unrelated 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 Luby's

What we can learn from LUB's beta value

Looking at the last five years, Luby's has a beta of 0.87. 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 suggests that including it in your portfolio will reduce volatility arising from broader market movements, assuming your portfolio's weighted average beta is higher than 0.87. 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 Luby's's revenue and earnings in the image below.

Could LUB's size cause it to be more volatile?

With a market capitalisation of US$71m, Luby's is a very small company by global standards. It is quite likely to be unknown to most investors. Companies with market capitalisations around this size often show poor correlation with the broader market because market volatility is overshadowed by company specific events, or other factors. It's worth checking to see how often shares are traded, because very small companies with very low beta values are often only thinly traded.