本研究以1996年至2002年間，78家在美國NYSE、NASDAQB、AMEX三大證券交易所之多角化決策宣告為事件研究樣本，利用各種衡量模型及基準報酬探討其宣告後長期股價報酬績效。實證結果發現在不同的基準報酬設定下，公司宣告多角化後一年、二年及三年有顯著正向長期異常報酬，顯示有利於提昇公司價值和股東財富。此外，公司存在低成長性、低獲利性、跨入部門數目較少與規模小等因素，皆會使長期股價報酬績效表現上升。

This study investigates 78 diversification firms which went public in United State during 1996-2002. We examine the impact of diversified announcement on the long run performance. The empirical results show that firms have superior performance than non-diversified firms over various methods and benchmarks. This article also addresses profit, growth and size as our explicatory factors.

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