Bruce Greenwald

Is a 20-year honeymoon coming to an end? When it comes to suspending disbelief about a lack of profits — the only thing that ultimately matters when it comes to stock valuation — Amazon.com has been in a class of its own. Its price-to-earnings ratio, a common measure of stock valuation, has at various times topped 3,000 (the market average is about 18), and that's when it actually has had a profit. Investors never seemed to care.