What's worth more — a company that sells $250 billion of stuff every year at a profit margin of 22%, or a company that sells $200 billion of stuff every year at a profit margin of 3%?
The answer: It's surprisingly close. Both Apple and Amazon now have a stock-market valuation of $1 trillion. The Apple valuation makes a lot of sense: If anything, the iPhone maker is undervalued by the standards of the stock market as a whole. But Amazon is another story entirely: each dollar of profit it makes is valued by the market at an eye-popping $208.