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If you're interested in Plug Power Inc. (NASDAQ:PLUG), 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. 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. A stock with a beta greater than one is more sensitive to broader market movements than a stock with a beta of less than one.

Check out our latest analysis for Plug Power

What does PLUG's beta value mean to investors?

Looking at the last five years, Plug Power has a beta of 1.43. The fact that this is well above 1 indicates that its share price movements have shown sensitivity to overall market volatility. If this beta value holds true in the future, Plug Power shares are likely to rise more than the market when the market is going up, but fall faster when the market is going down. Beta is worth considering, but it's also important to consider whether Plug Power is growing earnings and revenue. You can take a look for yourself, below.

Does PLUG's size influence the expected beta?

Plug Power is a small cap stock with a market capitalisation of US$562m. Most companies this size are actively traded. It is quite common to see a small-cap stock with a beta greater than one. In part, that's because relatively few investors can influence the price of a smaller company, compared to a large company.

What this means for you:

Since Plug Power has a reasonably high beta, it's worth considering why it is so heavily influenced by broader market sentiment. For example, it might be a high growth stock or have a lot of operating leverage in its business model. This article aims to educate investors about beta values, but it's well worth looking at important company-specific fundamentals such as Plug Power’s financial health and performance track record. I highly recommend you dive deeper by considering the following:

1. Future Outlook: What are well-informed industry analysts predicting for PLUG’s future growth? Take a look at our free research report of analyst consensus for PLUG’s outlook.

2. Past Track Record: Has PLUG been consistently performing well irrespective of the ups and downs in the market? Go into more detail in the past performance analysis and take a look at the free visual representations of PLUG's historicals for more clarity.

3. Other Interesting Stocks: It's worth checking to see how PLUG measures up against other companies on valuation. You could start with this free list of prospective options.

We aim to bring you long-term focused research analysis driven by fundamental data. Note that our analysis may not factor in the latest price-sensitive company announcements or qualitative material.

If you spot an error that warrants correction, please contact the editor at editorial-team@simplywallst.com. This article by Simply Wall St is general in nature. It does not constitute a recommendation to buy or sell any stock, and does not take account of your objectives, or your financial situation. Simply Wall St has no position in the stocks mentioned. Thank you for reading.