Vertical integration,foreclosure, and productive efficiency

We analyze the consequences of vertical integration by a monopoly producer dealing with two retailers (downstream firms) of varying efficiency via secret two‐part tariffs. When integrated with the inefficient retailer, the monopoly producer does not foreclose the rival retailer due to an output‐shifting effect. This effect can induce the integrated firm to engage in below‐cost pricing at the wholesale level, thereby rendering integration procompetitive. Output shifting arises with homogeneous and differentiated products. Moreover, we show that integration with an inefficient retailer emerges in a model with uncertainty over retailers' costs, and this merger can be procompetitive in expectation.