以往重複事件分析法主要用於醫學與科學領域，近來學者逐漸將其應用至經濟、商學、社會科學等領域，本篇論文採用重複事件分析法，分析S&P 500公司股票回購的行為，回顧過去學者對股票回購之研究，我們檢視公司執行股票回購的三大原因，根據我們的實證結果發現公司可能會以股票回購作為影響公司資本結構的工具，再者亦可能用以減低剩餘資金，然而，本篇論文的實證結果較不支持訊號發射理論。

In this study, we apply Cox proportional hazard model in recurrent event analysis, which usually used in medical and science studies, to analyze the determinants of the stock repurchase events of S&P 500 companies. We investigate three main incentives that companies conduct stock repurchase. The empirical results show that companies employ repurchase as a technique to alter capital structure. In addition, companies conduct stock repurchase to distribute excess capital. In contrast, there are little evidences to support signaling undervaluation.

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