Diversifying Mergers and Risk: A Comment

In his article “Diversifying Mergers and Risk: Some Empirical Tests”, Thompson (1983) modelled the change in the systematic risk of the acquiring firm before and after merger. We propose a modification to this method which considers the difference between the systematic risk of the merged firm and that predicted by capital market theory on the basis of the constituent firms' betas. Furthermore merger will probably lead to a change in the structure of the acquiring firm, both intrinsically and financially. Thus in order to remove any complications caused by debt restructuring of the combined firm after merger, we suggest that the analysis is carried out using ungeared or intrinsic betas. An empirical study which follows that of Thompson but implements the above modifications is performed, and conclusions are drawn which have implications for studies that have considered the benefits of merger to the acquiring and target firms.