eBay (EBAY) shareholders are feeling the effects of owning a stock with a 70 forward p/e tonight. With a equity market valuation that high, there leaves little room for error. You won't be able to find a single person who thought eBay would miss its earnings after the bell today, and as a result the stock fell $15 in early evening trading.

The great thing about Wall Street is that if you managed to avoid having eBay in your portfolio, you can take advantage tomorrow morning when investors throw the baby out with the bath water. It always happens, even when it defies logic. All Net stocks got crushed when eBay's earnings report came out. Yahoo! (YHOO), Overstock (OSTK), and Google (GOOG) especially. Just decimated.

Why? Because they are Internet companies. Only thing is, just because eBay feels it needs to invest in its business to maintain market dominance (which will lead to lower margins, hence, lower earnings per share), this doesn't mean anything is wrong at Yahoo!, or Google, or Overstock.

Yahoo! barely even remembers it has an auction site, eBay won that battle long ago. Google doesn't have auctions. Overstock said this week that it saw a huge rise in its auction listings after eBay announced its annual fee hikes (which were needed even more this year to help prop up falling profit margins). Nonetheless, all of these stocks lost 10 percent of their value just between noon and 5pm, solely due to eBay's announcement.

The market gives investors these types of opportunities all the time. The only problem is, most investors don't take advantage of them. They should.