Although firms often conduct multiple acquisitions simultaneously with overlapping procedures running in parallel, little is known about the consequences of parallel acquisitions on a focal acquisition’s integration planning. Drawing on information overload research and the attention-based view of the firm, we propose that parallel acquisitions may result in information overload in which managers with bounded rationality have constrained capacity to proceed the amount, the characteristics, and the flow of information. Leveraging a novel measure of integration decision quality – the underestimation of integration costs, we find that parallel acquisitions are associated with significantly higher likelihood of integration cost underestimation. Our paper advances acquisition research by introducing the effect of activity load on integration and by illuminating the cognitive challenges in managing parallel activities.