 Sales fell just short of what Wall Street was expecting. Profit beat. Investors didn't like what they heard, apparently. The shares are moving lower ahead of the opening bell. Amazon and other U.S. retailers are contending with the rapid rise of discount upstarts like Timu and Xien. Now Amazon is planning to launch an online storefront for low-priced clothing and home goods that are shipped directly from Chinese merchants to U.S. customers. The plans were described in slides posted to websites for third-party Chinese sellers.