本研究為觀察公司自由現金流量多寡是否會影響股票回購宣告後的股東財富，我們使用 2000年至 2020年間，共495家不同上市公司宣佈的1461件股票回購計畫作為樣本，並以 Tobin's Q 和自由現金流量進行分類，將High CF(自由現金流量大於樣本中位數)及Low Q(Tobin's Q<1)的公司定義為擁有自由現金流量公司。事件研究法實證結果顯示，擁有自由現金流量公司其股票回購宣告後的異常報酬顯著高於其他公司；為了測試結果穩健性，也進行橫斷面迴歸分析，加入了其他可能影響異常報酬的控制變數後，發現擁有自由現金流量公司仍然具有較高的短期或長期異常報酬，我們 認為自由現金流量假說可以充分解釋公司自由現金流量多寡對股票回購後的股東財富影響。

This study tests whether a firm's free cash flow affects shareholder wealth after the announcement of stock repurchases. We use a sample of 1,461 stock repurchase plans announced by 495 different listed companies between 2000 and 2020. The classification is based on Tobin's Q and free cash flow, where firms with high free cash flow (above the sample median) and low Q (Tobin's Q < 1) are defined as firms with free cash flow. According to the result of event study method, firms with free cash flow earn significantly higher abnormal returns than other firms. In cross-sectional regression analysis, firms with free cash flow still earn higher short-term or long-term abnormal returns after controlling for variables that could potentially affect abnormal returns. Therefore, we believe that the free cash flow hypothesis adequately explains the relationship between firm's free cash flow and shareholder wealth after the announcement of stock repurchases.

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