本研究主要探討從公司治理觀點檢視銀行合併與成本效率的關係，以民國83年到98年，樣本銀行共49家為主要研究對象，並區分為主併銀行與被併銀行。
本文為了在諸多公司治理指標中尋找有效的代表性指標，以因素分析法(factor analysis)中的主成份分析法(principal com-ponent analysis)，萃取出代表銀行業公司治理之主要成份。之後再納入合併變數及環境變數以設定無效率模型。第二部份採用Battese and Coelli (1995)之隨機生產函數模型，利用對偶理論，轉換設定隨機成本邊界模型同時進行一階段同時估計成本函數及無效率模型。
本文實證結果顯示，在銀行成本效率方面：(1)公股銀行最不具效率性，其次為泛公股銀行，民營銀行最具效率。(2)主併銀行的無效率值高。(3)分行數多不一定代表經營效率高。在公司治理方面：董監事規模、董監事質押比例與銀行成本無效率成正向且顯著關係，說明： (1)董監事規模小，對於銀行效率有負面影響。(2)董監事質押比例愈高，銀行發生財務風險機率提升。
This study investigates relationship between bank mergers and cost efficiency from corporate governance point of view. The research data are 49 sample banks in two categories, acquiring bank and acquired bank, from 1994 to 2009.
The method to extract effective representation index from a lot of corporate governance index that can stand for bank industry corporate governance principal constituent is using principal components analysis of factor analysis. The next step is to add merger variables and environment variables to set inefficiency model. The se-cond part is to use Battese and Coelli (1995) of the stochastic production function model and duality theory to transform setting stochastic cost function model and to estimated cost function and inefficiency model at the same time.
This empirical results give the following three conclusion about the bank cost efficiency: (1)state-owned banks is the least efficient, followed by the pan-owned banks, and private banks is the most efficient;(2)the acquiring bank inefficiency value is high; (3)the higher number of branches does not necessarily mean more efficient operation. In terms of corporate governance, there is strong and positive relationship between number of directors and supervisors, equity pledge ratio of directors and supervisors and bank cost inefficiency : (1)small numbers of directors and supervisors have a negative impact on bank efficiency;(2)The higher the equity pledge ratio of directors and supervisors, the higher is the risk percentage.
