Comment by 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.