We investigate the impact of merger on innovation and efficiency using a micro dataset of Japanese manufacturing firms including unlisted firms during the period of 1995-1999. We find that the acquirer's total factor productivity (TFP) decreases immediately after mergers and does not significantly recover to the pre-merger level within three years after mergers. We also find that the R&D intensity does not significantly change after mergers in spite of a significant increase in the debt-to-asset ratio. Our results suggest that the costs of business integration are large and persistent.

To take into considering large integration costs, we also analyze the post-merger performance from one year after mergers, finding no significant increase in TFP or R&D intensity up to three years after mergers.

Given the heterogeneity of mergers, we analyze the post-merger performance by classifying merger types. We find that the recovery of TFP after mergers is significant for mergers across industries or within the same business group, suggesting that a synergy effect works well and integration costs are small for those types of mergers.