公司董事會多樣性是否有助於降低公司風險？

The Linkage between Board Diversity and Corporate Risk

本研究根據2011~2014年間臺灣證券交易所786家上市非金融產業公司的資料，檢驗公司董事會多樣性（BoardDiversity）與公司風險的關聯性。既有研究指出，公司董事的主要功能為咨詢（Advising）、監督（Monitoring）以及提供外部資源（External Resource），就利益面來看，公司董事會成員的多樣性程度愈高，不同背景而相互互補的背景、特質、能力與專長有助於董事會效能的發揮，對於管理決策的形塑與品質有正面助益，有助於增進公司績效與降低公司風險。然而董事會多樣性的成本面亦包括董事會中不同群體所需的協調溝通成本以及表面上卻缺乏專業性的多樣性將有可能降低董事會的運作效率，使公司績效惡化並提高風險。本研究進一步擴充既有研究中關於董事會多樣性的維度，除了董事成員的性別多樣性外，包括董事成員的年資、學歷、忙碌性（兼任其他職的職位數）、財務、會計或法務專長之比例以及董事會獨立性，建構更全面性的董事會多樣性指標。公司風險指標採用公司會計績效的波動性以及股票市場表現波動性等九個指標作為代理變數。透過相關分析與多重迴歸估計結果發現，董事會多樣性指標與若干公司風險指標呈正向關聯，表示平均來說，公司董事會多樣性程度愈高，公司的風險是顯著相對較高的，特別是反應在較大的股票報酬率波動性上，這表示董事會多樣性產生的成本大於其利益。

Based on data of 786 listed nonfinancial firms on Taiwan Stock Exchange (TWSE) covering the period of 2011~2014, this paper examines the linkage between the degree of board diversity and several corporate risk indicators. To construct a more comprehensive board diversity index, in addition to board member gender diversity, other dimensions such as board member tenure, level of education, board busyness (multiple job-holdings), proportion of board member with professionals on finance/law/accounting and board independence are incorporated. Existing literature has indicated that main functions of board are managerial advising, managerial monitoring (Fama, 1980) and providing external resource. While a board room with greater degree of diversity tends to have divergent background, accumulated reputation, management knowledge and experience as well as tangible/intangible resources to promote advising and monitoring which in turn improve performance/reduce risk, diversified board may suffer from less consensus, conflict of interests and communication difficulties which in turns deteriorates the performance and fosters higher risk. Based on multiple regression estimation, empirical result generally shows that greater degree of board member diversity is associated with higher corporate risk in terms of higher volatility of firm’s stock returns, greater downside risk and higher market risk. The evidence supports the view that cost of board diversity is greater than its benefit.