The global athletic shoe market is expected to rise at a compound annual average growth rate of 1.8 percent between 2011 and 2018, according to Transparency Market Research, reaching a level of $84.4 billion at retail at the end of the period. That is roughly twice the size of the market estimated by Sporting Goods Intelligence at wholesale. According to the American research agency, athletic footwear would then represent 39.9 percent of a global footwear market projected at $211.5 billion. The agency also predicts that e-commerce and other forms of non-physical shoe retailing will grow by 6.9 percent a year to reach sales of $18.6 billion by 2018.