This paper analyses the sources of buyer power and its expect on sellers investment. We show that a retailer extracts a larger surplus from the negotiation with an upstream manufacturer the more it is essential to the creation of total surplus. In turn, this depends on the rivalry between retailers in the bargaining process. Rivalry increases when the retail market is more fragmented, when the retailers are less differentiated and when decreasing returns to scale in production are larger. The allocation of total surplus affects also the incentives of producers to invest in product quality, an instance of the hold up problem. This not only makes both the supplier and consumers worse off, but it may harm also the retailers.