We knew this day would come.

Amazon.com (NASDAQ:AMZN), the e-commerce juggernaut that has pioneered industries as diverse as online retail, e-books, and cloud computing, has been working toward this for ages: The day when its market value would best Wal-Mart Stores (NYSE:WMT).

Its dominance in e-commerce has gradually eroded Wal-Mart's growth, and the success of its cloud computing unit has assured investors that the company can, in fact, be profitable. Below, we take a further look at how Amazon was able to topple the big box retailer.