本研究對IC設計產業曾進行虧損減資、現金減資及庫藏股減資之公司，分別進行內外部分析。外部分析，係以事件研究法，探究減資宣告對於投資人之訊息效果；而內部分析則以五因子擴張杜邦方程式解析公司減資後之長期營運績效。 實證結果發現，在外部宣告效果上，虧損減資宣告存有負向異常報酬，顯示投資人不認為減資可帶領此類公司重獲新生；現金減資宣告存有正向異常報酬，顯示現金為王，投資人給予正面肯定；庫藏股減資則未出現明顯異常報酬。 而在內部後續營運績效上，虧損減資公司股東權益報酬率及營業利潤率僅在當年提升，而後下降；投入資本周轉率一路呈下滑趨勢；其餘績效指標不顯著。顯示虧損減資公司績效改善不彰。現金減資公司，可能因樣本量過低，效果不顯著。庫藏股減資公司，股東權益報酬率及投入資本周轉率在減資後大致呈逐年下降趨勢，但僅零星年度出現顯著效果；其餘績效指標不顯著；顯示減資並未對公司營運績效帶來太大影響。 This study incorporates different capital reduction on IC design Industry in Taiwan, to evaluate the external announcement effect and the internal operating performance by differing category, such as capital reduction to write off accumulated losses, cash refund capital reduction, and capital reduction by stock repurchases. The event-study methodology is used for the external analysis to explore the market response toward the announcements, and the Modified Five-factor Du Pont Formula is used for the internal analysis to measure the long-run operating performance after capital reduction. Based on the market announcement effect, the empirical results show that capital reduction to write off accumulated losses appears negative abnormal returns. It means that the investors don't think the prospects of such firms appear to be brightening. Cash refund capital reduction shows the positive effects after declaration, revealing that the securities market still gives higher rating to companies reducing capital by cash. And capital reduction by stock repurchases shows no effect after declaration. Based on the long-run operating performance, capital reduction to write off accumulated losses increases its return on equity and operating profit margin in event year but then declines, while capital turnover gets worse and the rest of the ratios have no significant difference between two variables (before versus after).To sum up, capital reduction to write off accumulated losses doesn't result in improved long-run operating performance after capital reduction. Perhaps due to too small sample size, there is no significant difference observed through statistical test among cash refund capital reduction firms. As to Capital reduction by stock repurchases, it goes down on its Return on equity and Operating profit margin, however only few years appear significant difference, and the rest of the DuPont ratios have no significant difference. The results indicate that Capital reduction by stock repurchases has limited influence on companies' long-run operating performance.