Amazon Took Data from Its Own Sellers to Develop Competing Products

The online retailing giant has long asserted, including to Congress, that when it makes and sells its own products, it doesn’t use information it collects from the site’s individual third-party sellers—data those sellers view as proprietary.

Yet interviews with more than 20 former employees of Amazon’s private-label business and documents reviewed by The Wall Street Journal (pay wall) reveal that employees did just that. Such information can help Amazon decide how to price an item, which features to copy or whether to enter a product segment based on its earning potential, according to people familiar with the practice, including a current employee and some former employees who participated in it.