If you're interested in Solitario Zinc Corp. (NYSEMKT:XPL), then you might want to consider its beta (a measure of share price volatility) in order to understand how the stock could impact your portfolio. 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 category is company specific volatility. This can be dealt with by limiting your exposure to any particular stock. The other type, which cannot be diversified away, is the volatility of the entire market. Every stock in the market is exposed to this volatility, which is linked to the fact that stocks prices are correlated in an efficient 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. 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 Solitario Zinc

What we can learn from XPL's beta value

Given that it has a beta of 1.53, we can surmise that the Solitario Zinc share price has been fairly sensitive to market volatility (over the last 5 years). If this beta value holds true in the future, Solitario Zinc shares are likely to rise more than the market when the market is going up, but fall faster when the market is going down. 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 Solitario Zinc's revenue and earnings in the image below.

Does XPL's size influence the expected beta?

Solitario Zinc is a rather small company. It has a market capitalisation of US$17m, which means it is probably under the radar of 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.