사건연구방법의 수평형 기업결합 효과 예측력 검증: 주식시장 자료와 회계 자료의 비교를 중심으로

This study provides empirical evidence of the predictability of the event study method in horizontal mergers. Using the horizontal merger sample of which merger control decisions were conducted by the Fair Trade Commission, we find that the expected profitability of competitors estimated by the event study method has a significant positive correlation with their ex-post profitability one year after the merger observed in the financial data. In particular, when we apply -5 to +10 days around the merger announcement date as the event window, the effect of merger measured as ex-post profitability one to five years after the merger is well predicted by the event study method. The predictive power of the merger effects varied across subsamples. The event study method well predicts the effect of merger derived by the ex-post profitability of competitors in anti-competitive mergers, but it is not effective in pro-competitive mergers. In addition, the merger with unconditional approval shows the best predictive power, and the merger with conditional approval has poor predictability. Our findings suggest that the event study method can be useful for predicting the effect of horizontal mergers, indicating that it has room for being used as reference material in the stage of merger review and ex-post evaluation.