企業社會責任對庫藏股宣告效果之影響

The Impact of Corporate Social Responsibility on Announcement Effect of Stock Repurchase

本研究欲探討當企業發生庫藏股宣告時，投入企業社會責任（Corporate Social Responsibility，簡稱CSR）之程度，是否對於企業自身股價之累積異常報酬（Cumulative Abnormal Returns，CAR）有所影響。採事件研究法分析之，事件日為首次出現在新聞媒體上之企業宣告購回庫藏股（Treasury Stocks）日期，研究期間為2006年至2009年。所探討之影響因子分別為企業CSR之短期投入，取事件日前一年CSR之總分；企業CSR之長期投入，為事件日前三年CSR總分之加權平均值；同產業CSR投入程度，則採宣告日前一年之產業平均。另採兩控制變數，包括市價淨值比及總資產，均採宣告日前一年資料；此外，增加一虛擬變數，將資料區分為金融海嘯發生前後，以驗證金融海嘯對CAR之影響。實證結果顯示，不論在短期投入、長期投入或同業間的投入，其投入多寡對庫藏股宣告所產生之累加異常報酬，大多無顯著之影響，即使有影響，也是負面影響且僅達10%顯著水準。此結果呼應學者所提CSR之類保險效果，亦即CSR之投入僅在企業面臨負面事件之衝擊下才能發揮其效果，減緩負面事件之衝擊；太平之時，僅會增加企業的財務支出，對其財務績效可能產生不良之影響。

This research was to discuss whether the investment amount of CSR (Corporate Social Responsibility) has impacts on CAR (Cumulative Abnormal Returns) of stock price during the announcement of stock repurchase. This research adopted event study from 2006 to 2009. The influential factors discussed were short-run input of CSR: the total score of CSR whole year before event day; long-run input of CSR: the weighted average score of CSR three years before event day; the input level of CSR within industry: the industrial average score whole year before event day. Two control variables were also adopted: MBR (Market-to-Book ratio) and total asset, both were whole year data before event day. In addition, one dummy variable were included to classified data into before/after financial crisis, to verify the influence of financial crisis on CAR. According to empirical result, regardless of short-run, long-run or industrial input, the amount of CSR has no significant influence on CAR, if any, negative influence and only achieved 10% significant level. Such result caters to the insurance-like effect of CSR introduced previously by scholars, which stated the input of CSR would only show effects when enterprises facing difficulties due to negative event as a buffer. However, it increases financial expenditure and might have negative influence on financial performance without negative events.