It took 18 years, and now online-retailer Amazon.com (AMZN) is a bigger company than big-box retailer Wal-Mart (WMT).  No, really, check out the chart of their market caps since AMZN went public in 1997.  After Wal-Mart’s recent stumbles and Amazon’s six-month surge, Jeff Bezos is now the king of retail as the Waltons take a back seat.