戦間期日本における企業合併と株式市場の評価

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抄録

In this paper, we examine the shareholder returns of both bidders and targets for approximately 20 major corporate mergers that occurred in the 1920s and 1930s. Our analysis yields the following findings. First, estimates of the premium, measured by changes in market capitalization, indicate that the premium was positive for the overall period, negative until the early 1930s, and positive again from the mid-1930s onward. Second, shareholder returns measured by abnormal returns were generally close to zero (or negative) for bidders and positive for targets. However, these responses varied across subperiods: bidder-side returns declined sharply during the 1930s, whereas target-side returns increased substantially during the same period. Third, regression analyses investigating the determinants of bidder shareholder returns show that relative performance had a significantly positive effect. In particular, the greater the potential for the transfer of know-how from bidders to targets, the larger the wealth gains for bidder shareholders. Fourth, premium levels did not directly affect bidder returns. Even transactions involving Nissan, which often paid relatively high premiums, were not necessarily valued positively by the market in the short term. However, these high premiums substantially increased the wealth of the target shareholders. Thus, the value-creating effects of the Nissan deals appear to have been asymmetrical between target and bidder shareholders. Although Nissan’s aggressive M&A strategy—often emphasized in the traditional literature on conglomerate history—did not immediately enhance group shareholder wealth from the bidder perspective, the positive premiums paid to target shareholders suggest that these transactions nonetheless generated value from the sell-side perspective.