Amazon copied products and rigged search results to promote its own brands
In Germany Amazon pressured third-party sellers to use their fulfillment/warehousing service, which would reveal to them where those sellers source their goods from. They then just went to those sources and offered them a better deal, cutting out the third-party seller. So basically third-party sellers are doing free market research for Amazon: They take on the entrepreneurial risk and if they're successful Amazon will know exactly how many goods they sell to which customers and from who they get those goods. They can then use that information in their own product strategy and simply take over the business of their most profitable sellers. Really clever strategy IMHO, albeit not very fair.