Tellgen Corporation (SZSE:300642) shareholders would be excited to see that the share price has had a great month, posting a 26% 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 27% over that time.

Following the firm bounce in price, Tellgen's price-to-earnings (or "P/E") ratio of 31.1x might make it look like a sell right now compared to the market in China, where around half of the companies have P/E ratios below 27x and even P/E's below 16x are quite common. Although, it's not wise to just take the P/E at face value as there may be an explanation why it's as high as it is.

As an illustration, earnings have deteriorated at Tellgen over the last year, which is not ideal at all. 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. You'd really hope so, otherwise you're paying a pretty hefty price for no particular reason.

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

There's an inherent assumption that a company should outperform the market for P/E ratios like Tellgen's to be considered reasonable.

Retrospectively, the last year delivered a frustrating 44% 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 54% 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.

In contrast to the company, the rest of the market is expected to grow by 36% over the next year, which really puts the company's recent medium-term earnings decline into perspective.

In light of this, it's alarming that Tellgen'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 Bottom Line On Tellgen's P/E

Tellgen shares have received a push in the right direction, but its P/E is elevated too. 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.

We've established that Tellgen currently trades on a much higher than expected P/E since its recent earnings have been in decline over the medium-term. 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. Unless the recent medium-term conditions improve markedly, it's very challenging to accept these prices as being reasonable.

It is also worth noting that we have found 4 warning signs for Tellgen (1 is potentially serious!) that you need to take into consideration.

Of course, you might find a fantastic investment by looking at a few good candidates. So take a peek at this free list of companies with a strong growth track record, trading on a low P/E.

Have feedback on this article? Concerned about the content? Get in touch with us directly. Alternatively, email editorial-team (at) simplywallst.com.
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.