Amazon is expected to surpass Macy’s to become the biggest apparel seller in the US this year. While Amazon has dominated overall online sales in the US for years, the site is a relative newcomer to the fashion world. The company’s swift success is due, in large part, to underwear sales, according to a new report by retail consulting firm One Click Retail. Men’s and women’s underwear and intimate apparel accounted for two out of five of Amazon’s top-selling apparel categories last year, for a total of $415 million in sales, according to the report. The No. 1-selling category was men’s bottoms ($375 million in sales) — which include pants and shorts — followed by women’s intimate apparel ($250 million), men’s workwear ($225 million), women’s denim ($170 million), men’s underwear ($165 million). Read more at Business Insider.