Anyone researching Beijing Capital International Airport Company Limited (HKG:694) 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. 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 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 can be a useful tool to understand how much a stock is influenced by market risk (volatility). However, Warren Buffett said 'volatility is far from synonymous with risk' in his 2014 letter to investors. So, while useful, beta is not the only metric to consider. To use beta as an investor, you must first understand that the overall market has a beta of 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.

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Check out our latest analysis for Beijing Capital International Airport

What 694's beta value tells investors

Beijing Capital International Airport has a five-year beta of 1.08. This is reasonably close to the market beta of 1, so the stock has in the past displayed similar levels of volatility to the overall market. If the future looks like the past, we could therefore consider it likely that the stock price will experience share price volatility that is roughly similar to the overall market. Share price volatility is well worth considering, but most long term investors consider the history of revenue and earnings growth to be more important. Take a look at how Beijing Capital International Airport fares in that regard, below.

Does 694's size influence the expected beta?

Beijing Capital International Airport is a reasonably big company, with a market capitalisation of HK$29b. Most companies this size are actively traded with decent volumes of shares changing hands each day. We shouldn't be surprised to see a large company like this with a beta value quite close to the market average. Large companies often move roughly in line with the market. In part, that's because there are fewer individual events that are signficant enough to markedly change the value of the stock (compared to small companies, at least).