本研究檢測董監事股票質押對公司維護信用及股東權益之股票買回決策的影響。因股票價格下跌時會提高質押股票保障額度不足的可能性，預期董監事股票高質押比率公司，有較高動機從事股票買回以維護公司股價。此外，因資訊競爭能有效地降低資訊不對稱程度，倘若資訊不對稱是董監事進行自利動機股票買回的因素，本研究預期資訊競爭程度將能減緩董監事股票質押對公司股票買回決策的影響。實證結果顯示：董監事股票質押比率與公司從事股票買回決策呈顯著正向關係，顯示董監事股票質押比率高時，公司從事股票買回宣告之可能性提高。在考慮資訊競爭的調解角色後，發現公司高資訊競爭程度可減緩董監股票質押對公司宣告買回之影響，然此減緩效果在金融危機發生後較明顯。本研究進行若干敏感性測試，發現實證結果具備相當的穩固性。

This study hypothesizes and tests whether high ratio of shares pledge by directors/supervisors is positively associated with a firm’s stock repurchases decision. Note that the degree of information competition can mitigate a firm’s information asymmetry, we thus further examine whether information competition plays a moderating role in the association between shares pledge by directors/supervisors and stock repurchases decision. The empirical results, as conjectured, show that high ratio of directors/supervisors’ share pledge is positively associated with stock repurchases and support the hypothesis. Further evidence reveals the information competition can effectively mitigate this positive relationship. However, this mitigating effect is more pronounced after the occurrence of global financial crisis in 2008. We demonstrate additional tests and show the results are robust to the various specifications.