What are the most expensive stocks in the market?

— -- Q: What are the most expensive stocks in the market right now?

A: When it comes to stocks, price is relative.

Momentum investors looking to jump in and out of stocks for a quick buck disagree with long-term investors over what stocks are pricey. And for that reason, it's very difficult to define what stocks are expensive in a way that all investors will agree.

But with that said, there are widely-agreed-upon benchmarks used to quantify how expensive stocks are. Among the most popular such valuation benchmarks is the price-to-earnings ratio, or P-E.

The P-E tells you how much investors are paying for a claim for every one dollar a company earns. The higher a stock's P-E, the higher its valuation.

Using this metric, investors can get a good idea of the stocks that are commanding the highest premiums from investors. The stocks with the highest P-Es, based on the S&P 500 index and earnings over the past 12 months, according to S&P Capital IQ:

Notice, though, I've been careful not to refer to the stocks above as being the most expensive. These are the stocks with the highest valuations. If these companies can deliver huge growth, they will justify their relatively high valuations and the stocks could even rise further.

But, there's no dispute that these are the stocks investors are paying top dollar for. Whether the high valuation is worth it is something that will be determined over the next few months or years.

Matt Krantz is a financial markets reporter at USA TODAY and author of Investing Online for Dummies and Fundamental Analysis for Dummies. He answers a different reader question every weekday in his Ask Matt column at money.usatoday.com. To submit a question, e-mail Matt at mkrantz@usatoday.com. Follow Matt on Twitter at: twitter.com/mattkrantz