Tianneng Power International Limited (HKG:819) shares have had a really impressive month, gaining 26% after a shaky period beforehand. The last 30 days bring the annual gain to a very sharp 28%.

Although its price has surged higher, given about half the companies in Hong Kong have price-to-earnings ratios (or "P/E's") above 10x, you may still consider Tianneng Power International as a highly attractive investment with its 4.7x P/E ratio. Nonetheless, we'd need to dig a little deeper to determine if there is a rational basis for the highly reduced P/E.

Tianneng Power International could be doing better as its earnings have been going backwards lately while most other companies have been seeing positive earnings growth. It seems that many are expecting the dour earnings performance to persist, which has repressed the P/E. If this is the case, then existing shareholders will probably struggle to get excited about the future direction of the share price.

See our latest analysis for Tianneng Power International

Keen to find out how analysts think Tianneng Power International's future stacks up against the industry? In that case, our free report is a great place to start.

Does Growth Match The Low P/E?

There's an inherent assumption that a company should far underperform the market for P/E ratios like Tianneng Power International's to be considered reasonable.

Retrospectively, the last year delivered a frustrating 6.3% 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 20% 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.

Shifting to the future, estimates from the two analysts covering the company suggest earnings should grow by 8.5% per annum over the next three years. Meanwhile, the rest of the market is forecast to expand by 13% each year, which is noticeably more attractive.

In light of this, it's understandable that Tianneng Power International's P/E sits below the majority of other companies. It seems most investors are expecting to see limited future growth and are only willing to pay a reduced amount for the stock.

The Bottom Line On Tianneng Power International's P/E

Even after such a strong price move, Tianneng Power International's P/E still trails the rest of the market significantly. 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 Tianneng Power International maintains its low P/E on the weakness of its forecast growth being lower than the wider market, as expected. Right now shareholders are accepting the low P/E as they concede future earnings probably won't provide any pleasant surprises. It's hard to see the share price rising strongly in the near future under these circumstances.

There are also other vital risk factors to consider and we've discovered 2 warning signs for Tianneng Power International (1 makes us a bit uncomfortable!) that you should be aware of before investing here.

Of course, you might also be able to find a better stock than Tianneng Power International. 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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