As online consumers become increasingly accustomed to shopping anytime and anywhere, thanks to the proliferation of smartphones and tablets, mobile commerce is growing at four times the rate of e-commerce overall in the U.S. And m-commerce is growing rapidly in other regions as well, as the just-released Internet Retailer 2014 Mobile 500 guide demonstrates.

The research guide estimates that the world's 500 largest mobile commerce businesses will increase their mobile sales by 71% this year to more than $30 billion. The 358 U.S. e-retailers ranked in the guide account for an estimated $25.4 billion, or 83%, of that global total. Including the $8.8 billion in mobile sales that will take place on eBay Inc.'s selling platform, U.S. mobile commerce sales will grow 63% to $34.2 billion, the Mobile 500 predicts. By contrast, e-retail sales in the U.S. last year grew 16%, according to the U.S. Department of Commerce.

Adding 100 retailers to the rankings of the 2013 Mobile 400 guide, the 2014 Mobile 500 ranks the 500 largest mobile commerce operators in North America, Europe and Asia based on their 2013 mobile sales. The research guide analyzes their mobile operations in never-before-revealed detail—including mobile traffic, site speed, conversion rate, average ticket, marketing features, mobile search engine scores, key vendors used and dozens of other metrics—in all up to 68 data elements for each business.

Recognizing that mobile growth is outpacing that of e-commerce overall, even small retailers, once content to rely upon eBay's platform to sell to mobile shoppers, are now building their own m-commerce sites and apps. In many cases, these mobile newcomers are eclipsing eBay's healthy 54% projected growth for this year, although eBay's $20 billion in expected mobile sales keeps it among the leaders in m-commerce. This shift to retailers building their own mobile sites and apps demonstrates the growing importance of mobile commerce.

"E-retailers around the world now understand that mobile is a game-changer for their businesses, and they're desperately looking to expand their existing mobile commerce businesses or build new ones," observes Internet Retailer publisher and chairman, Jack Love. "Our new Mobile 500 guide gives them the intelligence they need to compete in this explosive new segment of e-commerce."