Fortinet, Inc. (NASDAQ:FTNT) shareholders have had their patience rewarded with a 26% share price jump in the last month. The last 30 days bring the annual gain to a very sharp 31%.

Since its price has surged higher, given close to half the companies in the United States have price-to-earnings ratios (or "P/E's") below 17x, you may consider Fortinet as a stock to avoid entirely with its 43.5x P/E ratio. Although, it's not wise to just take the P/E at face value as there may be an explanation why it's so lofty.

Recent times have been pleasing for Fortinet as its earnings have risen in spite of the market's earnings going into reverse. The P/E is probably high because investors think the company will continue to navigate the broader market headwinds better than most. If not, then existing shareholders might be a little nervous about the viability of the share price.

What Are Growth Metrics Telling Us About The High P/E?

Fortinet's P/E ratio would be typical for a company that's expected to deliver very strong growth, and importantly, perform much better than the market.

If we review the last year of earnings growth, the company posted a terrific increase of 26%. Pleasingly, EPS has also lifted 171% in aggregate from three years ago, thanks to the last 12 months of growth. So we can start by confirming that the company has done a great job of growing earnings over that time.

Turning to the outlook, the next three years should generate growth of 12% per year as estimated by the analysts watching the company. Meanwhile, the rest of the market is forecast to expand by 10% per annum, which is not materially different.

In light of this, it's curious that Fortinet's P/E sits above the majority of other companies. Apparently many investors in the company are more bullish than analysts indicate and aren't willing to let go of their stock right now. These shareholders may be setting themselves up for disappointment if the P/E falls to levels more in line with the growth outlook.

The Key Takeaway

Shares in Fortinet have built up some good momentum lately, which has really inflated its P/E. We'd say the price-to-earnings ratio's power isn't primarily as a valuation instrument but rather to gauge current investor sentiment and future expectations.

We've established that Fortinet currently trades on a higher than expected P/E since its forecast growth is only in line with the wider market. Right now we are uncomfortable with the relatively high share price as the predicted future earnings aren't likely to support such positive sentiment for long. This places shareholders' investments at risk and potential investors in danger of paying an unnecessary premium.

Many other vital risk factors can be found on the company's balance sheet. Take a look at our free balance sheet analysis for Fortinet with six simple checks on some of these key factors.

If P/E ratios interest you, you may wish to see this free collection of other companies with strong earnings growth and low P/E ratios.

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This article by Simply Wall St is general in nature. We provide commentary based on historical data and analyst forecasts only using an unbiased methodology and our articles are not intended to be financial advice. It does not constitute a recommendation to buy or sell any stock, and does not take account of your objectives, or your financial situation. We aim to bring you long-term focused analysis driven by fundamental data. Note that our analysis may not factor in the latest price-sensitive company announcements or qualitative material. Simply Wall St has no position in any stocks mentioned.