權力遊戲：探討CEO雙重身份對公司績效之時間性效果

Abstract

針對CEO雙重身份，即CEO同時擔任董事長之議題，於過去數十年間，在學界、實務界及政策制訂者之間有相當廣泛之討論。即使過去針對CEO雙重身份有相當豐富之研究，CEO雙重身份對公司績效之影響究竟為何，至今仍無明確之研究結論。本研究透過嶄新之panel matching/weighting計量方法，重新檢視CEO雙重身份對公司績效之影響，試圖更有效處理過去文獻中經常面臨之因果關係推論之挑戰。使用常見之公司績效代理變數，例如：資產報酬率、毛利率及淨利率等，本研究發現過去文獻中未曾發現之CEO雙重身份對公司績效之動態影響。CEO雙重身份於三至五年之短期內，對公司績效產生正向影響。然而，約於第六年後，CEO雙重身份對公司績效開始產生負向影響。本研究顯示CEO雙重身份於短期內對公司績效產生正向影響，然而過度集中之權力將為公司長期績效埋下隱患，導致CEO雙重身份對公司長期績效產生負向影響。透過描繪CEO雙重身份對公司績效之動態影響，本研究對於CEO雙重身份之討論提供新的見解，亦試圖調和過去文獻中不一致之研究結果。

The debate over CEO duality—where the CEO also serves as the board chair—has captivated researchers, practitioners, and policymakers for decades. Despite extensive research, the impact of CEO duality on firm performance remains contentious and unresolved, plagued by endogeneity issues. This study revisits the CEO duality effect using cutting-edge panel matching and weighting methods to address these causal inference challenges. I scrutinize key performance indicators such as return on assets, gross profit rate, and profit margin. The results reveal a fascinating temporal dynamic: CEO duality significantly boosts firm performance in the short term, with positive effect lasting about 3 to 5 years. However, this initial boost gives way to a decline in performance, turning negative and statistically significant around 6 years after adopting CEO duality. This study suggests that the initial concentration of power in CEO duality eventually sows the seeds for a decline in performance. By mapping out these dynamic patterns, this study offers fresh insights into the CEO duality debate and helps reconcile the conflicting evidence found in prior research.