According to an estimate by the U.S. Commerce Department, e-commerce sales totaled $50.27 billion in the first quarter, up 15.4% from $43.58 billion in the first quarter of 2011. It is the first time e-commerce sales have topped $50 billion outside the fourth quarter, the busiest quarter for online sales. This figure accounts for 4.9% of total retail spending in the quarter, up from 4.6% a year ago.