本篇論文探討公司買回庫藏股的風險移轉效果。Maxwell and Stephens（2003）認為公司買回庫藏股司以將債權人的財富部份移轉給股東，所以債券市場對庫藏股的宣告有負面的反應。在庫藏股財富移轉機制下，本論文進一步提出部分公司買回庫藏股具有風險移轉的目的。當公司面臨財務危機與風險時，透過庫藏股的宣告與實施，公司可以將原本由股東與債權人共同分擔的風險，部分轉移至債權人身上。本論文研究4,010筆美國上市公司宣告買回庫藏股的事件，實證結果發現Z-Score最小的那一群公司宣告買回庫藏股時，有正的異常報酬。同時，本論文也發現該群公司有偏低的營運資金與偏高的負債比率。這些證據都支持公司宣告買回庫藏股時，對於潛在發生財務危機公司的股東而言是正面的訊息。

　　This paper investigates the risk-shifting effect of share repurchase activities. Maxwell and Stephens (2003) argue that repurchase may damage the bond price though it increases the shareholders' wealth. Following Maxwell and Stephens (2003), we further propose a risk­shifting hypothesis. For the potential distress firms, they might buyback shares to reduce shares outstanding by lifting debt ratio. Consequently, stockholders who reduce their position on the potential distress stocks tend to positively react to the repurchase announcements. Based on 4,010 repurchase announcements in U.S., we find that lowest Z-Score firms have positive repurchase announcement return and high leverage ratio. Even controlling traditional factors (undervaluation and leverage, for example), empirical findings still support our hypothesis.