Actually, their P/E ratio has been steadily declining over the past five years, even as their stock price has risen dramatically. Usually a stock is considered overvalued if the P/E ratio is really high. But this chart (stock price on top, P/E ratio on bottom) seems to indicate that AAPL is not being overvalued by the market as the stock price goes up: http://bigcharts.marketwatch.com/advchart/frames/main.asp?ti...
But investors are putting their money in to sell high since APPL doesn't pay dividends. The price is high atm, and there are many who are waiting exit, so any kind of trigger could set off a landslide.
