Amazon (AMZN) likes to undercut rivals’ prices on everything but this: Its stock price.

The online retailer’s shares are now trading for 942 times diluted earnings over the past twelve months – making them most expensive in the Standard & Poor’s 500, according to a USA TODAY analysis of data from S&P Capital IQ. It’s also the only stock in the index that has currently cracked the 900 price-to-earnings barrier.

Amazon is certainly in a class of its own when it comes to valuation, but it isn’t alone in pushing the measure. There are now 14 stocks in the S&P 500, including video streamer Netflix (NFLX) and social media king Facebook (FB), that are trading for 100 times or more their diluted earnings the past 12 months before extraordinary items.

Seeing such huge valuations offer a bit of deja vu for investors – who have been enjoying the market’s march higher the past few years. With the financial crisis and battered stock prices a distant memory, investors are again showing they’re willing to pay up – very dearly in same cases – for stocks. The P-E on the S&P 500 is now 20 based on operating earnings, says S&P Dow Jones Indices. That’s above the market’s average 18.8 valuation on that basis since 1988.

Some companies are certainly attracting more than their fair value of appreciation. Amazon’s P-E isn’t just high relative to the market – but the stock is richly valued even if the company achieves the high expectations investors have. Amazon’s P-E’s is now 14 times higher than the astounding 67% annual growth analysts expect long term from the company. That’s an off-the-charts valuation using traditional rules of thumb. Investors start to think a stock is pricey when its P-E is just 2 times its expected growth rate.

Online streamer, Netflix, is no slouch when it comes to what its earnings are worth to investors, either. Shares of the company’s stock are up 130% this year – pushing its P-E on trailing diluted earnings to 292. While that valuation is well below what Amazon commands, it’s still nearly 7 times the 44% long-term growth expected from the company by analysts.

Facebook is the latest high-tech company to bust into the ratified air of sky-high valuations. The company, which was criticized as a fad by skeptics during its 2012 initial public offering, is now one of the most richly prized stocks with a P-E of 107 times earnings. Analysts are calling for the company to grow nearly 30% a year on average over the long-term, showing just how much investors think of the stock.

It’s important to note that while these companies are commanding impressive valuations – they’re nowhere near the levels seen during the dot-com boom. Amazon, for instance, didn’t even have a P-E in March 2000 when the Nasdaq composite peaked because the company was still losing money. Amazon’s valuation today is far from Yahoo (YHOO)’s 2,225 PE in March 2000. Yahoo has has a lofty 135 P-E today, but that’s nowhere near what it was during the dot-com boom. The company may never justify what investors paid for it. Fifteen years after the dot-com peak, the online media company’s stock is down 43% even though its earnings are up 525% since then. Such underperformance in the stock price – despite improved profitability – shows that valuations do matter.

Some of these companies’ valuations aren’t sky-high because of soaring stock prices, but instead, of falling profits. Struggling office supply chain Staples (SPLS) still has a price-to-earnings ratio of 160 – despite the stock falling 29% this year. The stock simply isn’t falling as rapidly as profit – making the stock look expensive. The company reported diluted earnings per share of just 8 cents over the past 12 months, down 62% from the fiscal year ended January 2015 and off 92% from the fiscal year ended January 2014.

History has proven it’s still possible to make money on stocks with high valuations. Investors ridiculed for “overpaying” for Amazon in 2000 have gotten the last laugh as the stock is up nearly 900% since the Nasdaq peaked. Amazon could also very well grow into its valuation. The stock is trading for a “mere” 120 times the $5.50 a share it’s expected to earn in 2016.

But eventually – valuations do matter.

S&P 500 STOCKS WITH THE HIGHEST VALUATIONS *

Company, Symbol, P-E

Amazon, AMZN, 942.2

Computer Sciences, CSC, 439.4

Netflix, NFLX, 298.2

Tenet Healthcare, THC, 182.3

Staples, SPLS, 160.4

Perrigo, PRGO, 157.6

Alexion Pharmaceuticals, ALXN, 156.7

Yahoo, YHOO, 134.6

Halliburton, HAL, 127.5

Zimmer Biomet, ZBH, 112

Regeneron Pharmaceuticals, REGN, 109.3

Facebook, FB, 107.9

CR Bard, BCR, 105.2

Level 3, LVLT, 100.2

Sources: S&P Capital IQ, USA TODAY

* Based on P-E on diluted earnings the past twelve months before extraordinary items

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