The economic ambivalence of buyer power lies in its inherent potential to create efficiencies by reducing input costs. An antitrust policy which focuses exclusively on the reduction of competition on an input market is therefore prone to miss out on the consumer benefits created by powerful buyers. While a mere rent shifting from suppliers to downstream customers should not be objectionable under a consumer welfare approach, the exercise of buyer power may nonetheless be inclined to support downstream monopolization in the long run. Weighing those pro- and anticompetitive effects is an intricate issue. Can the Gordian Knot be cut by recognizing ‘supplier welfare’ as an additional goal for antitrust policy? The present chapter hones in on these issues under Article 102 TFEU, taking into consideration the stances of the US agencies.