Sundy Service Group Co. Ltd (HKG:9608) shares have had a really impressive month, gaining 30% after a shaky period beforehand. The last 30 days bring the annual gain to a very sharp 66%.

Since its price has surged higher, Sundy Service Group's price-to-earnings (or "P/E") ratio of 66.2x might make it look like a strong sell right now compared to the market in Hong Kong, where around half of the companies have P/E ratios below 9x and even P/E's below 5x are quite common. However, the P/E might be quite high for a reason and it requires further investigation to determine if it's justified.

For instance, Sundy Service Group's receding earnings in recent times would have to be some food for thought. One possibility is that the P/E is high because investors think the company will still do enough to outperform the broader market in the near future. If not, then existing shareholders may be quite nervous about the viability of the share price.

How Is Sundy Service Group's Growth Trending?

The only time you'd be truly comfortable seeing a P/E as steep as Sundy Service Group's is when the company's growth is on track to outshine the market decidedly.

Retrospectively, the last year delivered a frustrating 72% decrease to the company's bottom line. This means it has also seen a slide in earnings over the longer-term as EPS is down 82% 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 18% shows it's an unpleasant look.

In light of this, it's alarming that Sundy Service Group's P/E sits above the majority of other companies. Apparently many investors in the company are way more bullish than recent times would indicate and aren't willing to let go of their stock at any price. Only the boldest would assume these prices are sustainable as a continuation of recent earnings trends is likely to weigh heavily on the share price eventually.

The Bottom Line On Sundy Service Group's P/E

The strong share price surge has got Sundy Service Group'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 Sundy Service Group 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. When we see earnings heading backwards and underperforming the market forecasts, we suspect the share price is at risk of declining, sending the high P/E lower. 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.

Plus, you should also learn about these 5 warning signs we've spotted with Sundy Service Group (including 2 which don't sit too well with us).

Of course, you might also be able to find a better stock than Sundy Service Group. 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.

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