Better yet, a second theory would challenge Amazon’s conduct overall. A range of its particular actions over a few decades potentially makes out a claim, even under our current antitrust law, of illegal monopolization (in technical terms, a claim under Section 2 of the Sherman Act, rather than a merger challenge under Section 7 of the Clayton Act). The claim would be that this new acquisition and a series of prior acquisitions and other actions have delivered a market position in which Amazon is such a powerful buyer that it can force its suppliers to sell at subcompetitive prices. While monopsony claims are rare and difficult to bring, Amazon is no ordinary antitrust defendant. To prove the claim, the government could first show that Amazon has very large shares of sales in specific products and that those shares reflect actual market power because Amazon has acquired truly, historically unique economies of scope that no retail entrant could meaningfully challenge. The government could then show that these shares were acquired not by healthy, price-competitive vigor (in which case they would not be illegal). Rather, they were gotten through a series of acquisitions that may not have been individually illegal but in combination were monopolistic and by other exclusionary acts. A variety of the latter are well-documented, as, for example, Amazon’s use of its Amazon Marketplace platform to gather analytics on its Marketplace partners, then to enter their markets while using its data advantage and crushing terms to overtake the space.
Crack Down on Amazon – Slate Magazine