We examine the effect of buyer-side M&As on the continuation of supplier-buyer ties, distinguishing between the supplier’s and the buyer’s incentives to keep their relationship going. We focus on post-M&A changes in competitive overlap between the merged company and the other clients in the focal supplier’s customer base. We test our hypotheses on a sample of 798 advertising agency-client ties, for which the client was involved in an acquisition. Our results show that, from the buyer’s perspective, an increase in competitive overlap has a negative effect on the likelihood of tie continuation which is moderated by the relative intensity of investment in the service provided by the focal suppliers. From the supplier’s perspective we find that the negative effect of an increase in competitive overlap on the likelihood of tie continuation is moderated by the importance of the buyer to the supplier. Our results suggest that buyers are concerned about sharing a supplier with competitors, but these fears are mitigated when they are in a better bargaining position and they can use their power to force suppliers to put protective mechanisms in place.