Did Amazon Just Become the Largest Retailer in the World?

Is it official? Amazon (AMZN -0.73%) has been chasing Walmart (WMT -0.96%) as the largest company in the world by sales for years. Amazon's sales typically grow at a faster rate than Walmart's, but although the gap has been closing for a while, Walmart has been growing fast enough to maintain its lead.However, that might be about to change. After Amazon's smashing fourth quarter, it might be pulling ahead in the race. Let's see what's happening with these two giants and how that might affect your investing ...