Guru investor Carl Icahn said that U.S. stock market investors should tread carefully after the run up on Wall Street. Icahn said, "In my mind, it is time to be cautious about the U.S. stock markets. While we are having a great year, I am being very selective about the companies I purchase." The S&P 500 dropped as much as 1% and rebounded before closing down -0.41%. For month Uncle Carl has been pressing discount retailer Family Dollar Stores Inc to sell itself, today the company announced its profits fell by a third while it cleared inventory ahead of planned store closures.