Those holding CarGurus (NASDAQ:CARG) shares must be pleased that the share price has rebounded 44% in the last thirty days. But unfortunately, the stock is still down by 36% over a quarter. But shareholders may not all be feeling jubilant, since the share price is still down 44% in the last year.

Assuming no other changes, a sharply higher share price makes a stock less attractive to potential buyers. While the market sentiment towards a stock is very changeable, in the long run, the share price will tend to move in the same direction as earnings per share. The implication here is that deep value investors might steer clear when expectations of a company are too high. Perhaps the simplest way to get a read on investors' expectations of a business is to look at its Price to Earnings Ratio (PE Ratio). A high P/E implies that investors have high expectations of what a company can achieve compared to a company with a low P/E ratio.

View our latest analysis for CarGurus

Does CarGurus Have A Relatively High Or Low P/E For Its Industry?

We can tell from its P/E ratio of 60.77 that there is some investor optimism about CarGurus. The image below shows that CarGurus has a higher P/E than the average (26.9) P/E for companies in the interactive media and services industry.

Its relatively high P/E ratio indicates that CarGurus shareholders think it will perform better than other companies in its industry classification. Shareholders are clearly optimistic, but the future is always uncertain. So investors should delve deeper. I like to check if company insiders have been buying or selling.

How Growth Rates Impact P/E Ratios

Earnings growth rates have a big influence on P/E ratios. When earnings grow, the 'E' increases, over time. Therefore, even if you pay a high multiple of earnings now, that multiple will become lower in the future. So while a stock may look expensive based on past earnings, it could be cheap based on future earnings.

CarGurus's earnings per share fell by 37% in the last twelve months.

A Limitation: P/E Ratios Ignore Debt and Cash In The Bank

It's important to note that the P/E ratio considers the market capitalization, not the enterprise value. In other words, it does not consider any debt or cash that the company may have on the balance sheet. Theoretically, a business can improve its earnings (and produce a lower P/E in the future) by investing in growth. That means taking on debt (or spending its cash).

Such expenditure might be good or bad, in the long term, but the point here is that the balance sheet is not reflected by this ratio.

Is Debt Impacting CarGurus's P/E?

Since CarGurus holds net cash of US$172m, it can spend on growth, justifying a higher P/E ratio than otherwise.

The Bottom Line On CarGurus's P/E Ratio

With a P/E ratio of 60.8, CarGurus is expected to grow earnings very strongly in the years to come. Falling earnings per share is probably keeping traditional value investors away, but the relatively strong balance sheet will allow the company time to invest in growth. Clearly, the high P/E indicates shareholders think it will! What is very clear is that the market has become significantly more optimistic about CarGurus over the last month, with the P/E ratio rising from 42.1 back then to 60.8 today. If you like to buy stocks that have recently impressed the market, then this one might be a candidate; but if you prefer to invest when there is 'blood in the streets', then you may feel the opportunity has passed.

Investors should be looking to buy stocks that the market is wrong about. People often underestimate remarkable growth -- so investors can make money when fast growth is not fully appreciated. So this free visualization of the analyst consensus on future earnings could help you make the right decision about whether to buy, sell, or hold.

You might be able to find a better buy than CarGurus. If you want a selection of possible winners, check out this free list of interesting companies that trade on a P/E below 20 (but have proven they can grow earnings).

If you spot an error that warrants correction, please contact the editor at editorial-team@simplywallst.com. This article by Simply Wall St is general in nature. It does not constitute a recommendation to buy or sell any stock, and does not take account of your objectives, or your financial situation. Simply Wall St has no position in the stocks mentioned.

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