[sciolizer]

Depends on what you mean by "decline". But if you're talking about stock price, then the current Shiller PE Ratios are:

Amazon = 238.08 Netflix = 219.32 Google = 73.95 Facebook = 68.36 Apple = 63.17

The Shiller PE Ratio of the S&P 500 is current ~30. All of these companies are overpriced, and Amazon and Netflix significantly so.

[jandrewrogers]

PE ratios are only meaningful for comparing companies with no revenue growth, which is well-understood by investors. For companies with insanely high revenue growth, like Amazon, a PE ratio is essentially meaningless because that growth is financed with earnings. The fact that Amazon is only trading at 3.7x revenue is a strong argument that it is underpriced given its revenue growth, not overpriced.