The Spinoff and Merger Ex-Date Effects
发现分拆和换股合并的财富效应部分发生在可预测的除权日，分拆除权日平均超额收益3.0%，合并除权日平均超额收益1.5%。
This article shows that some of the wealth gains from financial decisions involving changes in security form occur on predictable ex dates. For a sample of 113 spinoffs during 1964 to 90, we document an average excess return of 3.0 percent on ex dates, roughly the same magnitude as the average announcement-date return. We conjecture that the spinoff ex-date return arises because the parent and subsidiary stocks attract different investors who prefer to buy the separated shares after the ex date. We also document that, on average, the target shareholders in stock-for-stock mergers earn an excess return of 1.5 percent on merger ex dates.