股權結構、董事會特性與公司績效之關係，為當代組織策略學者廣泛討論之議題。現有文獻中，股權集中度與董事年資對於公司績效到底有正向或負向的影響，卻有不一致的研究結果。本研究實證探討股權結構（包括大股東股權集中度、外部法人持股）與外部董事年資對公司績效之影響，採用2011 至2013 年台灣708 家上市公司的三年期資料。研究結果發現，大股東股權集中度與公司績效之間並非現有文獻主張的單純線性關係，而是先升後降的倒U 型曲線關係；同樣地，外部法人持股比例與外部董事年資，對於公司績效同樣存在先升後降的倒U 型曲線關係。本研究的結果對於過往學術研究的不一致結論，提供了可能的學術解釋。

The relationship between ownership structure, board composition and firm performance has been an increasingly important topic in organization and strategy research. Regarding whether shareholding concentration and director tenure have a positive or negative impact on firm performance, existing literature however reports inconsistent findings. This study empirically examines how shareholding structure (specifically, large shareholding and institutional shareholding) and outside director tenure influence firm performance, by using data collected from 708 Taiwanese public firms during the period of 2011-2013. The results show that large shareholding, institutional shareholding and outside director tenure influence firm performance in a nonlinear manner. Their influences are positive in the beginning and turn into negative when going beyond a certain degree, suggesting an inverted U-shaped relationship. Findings of this study are expected to shed new lights on the inconsistent findings of prior academic studies.