Abstract: We show that during the period of the Public Sector Purchase Program (PSPP) implemented by the Eurosystem, the prices of German sovereign bonds targeted by the PSPP increase predictably towards month-end and drop subsequently. We propose a sequential search-bargaining model that captures salient features of the implementation of the PSPP such as the commitment to buy within an explicit time horizon. The model can explain the predictable pattern as a result of imperfect competition between dealers that are counterparties to the Eurosystem. Motivated by the model's predictions, we show that the price pattern is more pronounced (a) for bonds that are targeted by the PSPP, (b) for monthly windows where the Eurosystem has fewer counterparties, and (c) for monthly windows where the Eurosystem targets a larger amount of purchases. We discuss the implications of our analysis for future purchase programs