ComNav Technology Ltd. (SHSE:688592) shareholders would be excited to see that the share price has had a great month, posting a 28% gain and recovering from prior weakness. Unfortunately, the gains of the last month did little to right the losses of the last year with the stock still down 34% over that time.

Since its price has surged higher, given close to half the companies in China have price-to-earnings ratios (or "P/E's") below 29x, you may consider ComNav Technology as a stock to avoid entirely with its 67.3x 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.

For instance, ComNav Technology's receding earnings in recent times would have to be some food for thought. It might be that many expect the company to still outplay most other companies over the coming period, which has kept the P/E from collapsing. You'd really hope so, otherwise you're paying a pretty hefty price for no particular reason.

Does Growth Match The High P/E?

In order to justify its P/E ratio, ComNav Technology would need to produce outstanding growth well in excess of the market.

If we review the last year of earnings, dishearteningly the company's profits fell to the tune of 12%. This means it has also seen a slide in earnings over the longer-term as EPS is down 38% in total over the last three years. So unfortunately, we have to acknowledge that the company has not done a great job of growing earnings over that time.

Weighing that medium-term earnings trajectory against the broader market's one-year forecast for expansion of 36% shows it's an unpleasant look.

In light of this, it's alarming that ComNav Technology's P/E sits above the majority of other companies. It seems most investors are ignoring the recent poor growth rate and are hoping for a turnaround in the company's business prospects. There's a very good chance existing shareholders are setting themselves up for future disappointment if the P/E falls to levels more in line with the recent negative growth rates.

The Key Takeaway

The strong share price surge has got ComNav Technology's P/E rushing to great heights as well. Using the price-to-earnings ratio alone to determine if you should sell your stock isn't sensible, however it can be a practical guide to the company's future prospects.

Our examination of ComNav Technology revealed its shrinking earnings over the medium-term aren't impacting its high P/E anywhere near as much as we would have predicted, given the market is set to grow. Right now we are increasingly uncomfortable with the high P/E as this earnings performance is highly unlikely to support such positive sentiment for long. If recent medium-term earnings trends continue, it will place shareholders' investments at significant risk and potential investors in danger of paying an excessive premium.

It is also worth noting that we have found 2 warning signs for ComNav Technology (1 is concerning!) that you need to take into consideration.

Of course, you might also be able to find a better stock than ComNav Technology. So you may wish to see this free collection of other companies that have reasonable P/E ratios and have grown earnings strongly.

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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.