Abstract: We examine the announcement and post-acquisition share returns of UK acquirers in over 4,000 acquisitions of domestic, cross-border, public and private targets. Domestic public acquisitions result in negative announcement and post-acquisition returns, whilst cross-border public acquisitions result in zero announcement returns and negative post-acquisition returns. In contrast, both domestic and cross-border private acquisitions result in positive announcement returns and zero post-acquisition returns. The main differences between private and public acquisitions are that glamour acquirers underperform in public acquisitions but not in private acquisitions, and that acquirers using noncash methods of payment underperform in domestic public acquisitions but not in domestic private acquisitions. Overall, cross-border acquisitions result in lower announcement and long run returns than domestic acquisitions. In cross-border acquisitions, those involving high-tech firms perform relatively well, as do those with low national cultural differences.