When close to half the companies in the United States have price-to-earnings ratios (or "P/E's") below 16x, you may consider Granite Construction Incorporated (NYSE:GVA) as a stock to avoid entirely with its 55.8x P/E ratio. However, the P/E might be quite high for a reason and it requires further investigation to determine if it's justified.

With earnings that are retreating more than the market's of late, Granite Construction has been very sluggish. One possibility is that the P/E is high because investors think the company will turn things around completely and accelerate past most others in the market. If not, then existing shareholders may be very nervous about the viability of the share price.

How Is Granite Construction's Growth Trending?

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

Taking a look back first, the company's earnings per share growth last year wasn't something to get excited about as it posted a disappointing decline of 47%. At least EPS has managed not to go completely backwards from three years ago in aggregate, thanks to the earlier period of growth. Accordingly, shareholders probably wouldn't have been overly satisfied with the unstable medium-term growth rates.

Turning to the outlook, the next year should generate growth of 329% as estimated by the five analysts watching the company. Meanwhile, the rest of the market is forecast to only expand by 11%, which is noticeably less attractive.

In light of this, it's understandable that Granite Construction's P/E sits above the majority of other companies. It seems most investors are expecting this strong future growth and are willing to pay more for the stock.

What We Can Learn From Granite Construction's 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 Granite Construction maintains its high P/E on the strength of its forecast growth being higher than the wider market, as expected. At this stage investors feel the potential for a deterioration in earnings isn't great enough to justify a lower P/E ratio. It's hard to see the share price falling strongly in the near future under these circumstances.

Don't forget that there may be other risks. For instance, we've identified 2 warning signs for Granite Construction that you should be aware of.

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.