董事兼職會影響新上市上櫃公司的後續績效表現嗎？

Director’s Multiple Jobholding and Subsequent Performance on Newly-Listed Companies

本文根據2008~2013 年間臺灣新上市、櫃公司的資料，檢驗董事會的忙碌程度(董事會成員兼職情形)是否影響公司上市後績效表現。本文認為新上市上櫃的公司有可能為了拉高承銷價格或達到上市上櫃的標準，進而窗飾公司的財報與相關訊息，使其在上市一段期間後出現股價與會計績效接連下跌的情形，這有可能導致股東財富的財務損失並在公司治理上表現為一種公司內部人或控制型股東擷取其他股東財富的可能性。公司董事會是重要的公司治理內部機制，董事會透過監督、提供諮詢與外部資源等功能以增進公司管理決策的品質與營運績效。本文認為董事會董事成員的忙碌(兼職情形)所累積的經驗與知識與外部資源有助於監督與咨詢功能的發揮，降低上市上櫃後績效衰退的幅度；然而，另一方面，董事兼職亦有可能稀釋其在特定公司從事監督與咨詢的投入努力，以致於惡化績效衰退的嚴重性。基本實證結果發現，大多數新上市櫃公司其上市櫃後的股票累積超額報酬率顯著為負，而上市櫃後的會計績效表現亦相對於上市櫃前要來得差，這表示新上市櫃公司在掛牌交易後的績效衰退情形是存在的。透過迴歸估計發現，在2008~2009年間董事會的忙碌性會降低上市櫃後會計績效的衰退幅度，支持忙碌董事成員擁有較多外部資源與較佳聲譽愈能效率地發揮監督與咨詢功能以增進公司績效表現的論點。考慮兩階段估計以矯正公司董事會忙碌性之內生性選擇偏誤下的實證結果具一致性。

This paper examines the linkage between the degree of board busyness (multiple job-holding by board member) and subsequent performance (stock returns and accounting indicators) on newly listed companies on Taiwan Stock Exchange and Gre-Tai Securities Markets. While newly-listed firms may inflate performance to obtain higher listed price or reach listed standard by window-dressing or earnings management, their corporate performance (market performance versus accounting performance) may deteriorate from pre-listed to post-listed period. Board busyness (proxied by multiple job-holding by board members) may strengthen/weaken the degree of performance decline through board functioning, e.g., monitoring, advising and providing outside resource. The univariate outcome shows that post-listed performance on stock returns were significantly negative and accounting indicators were also declined relative to pre-listed period, means that newly-listed firms were underperformed during pre-listed period. The multivariate analysis result shows that greater degree of board busyness mitigates the degree of underperformance during 2008~2009 but not on 2010~2013, and the result partially supports the view that busy director with greater outside resources and reputation which enhances the efficiency of board monitoring and advising, helps to lessen the severity of underperformance of newly-listed firms. Principal outcome changed little under two-stage estimation to correct for self-selection on corporate board busyness.