大股東護盤動機之探討

The Motive to Execute Open Market Share Repurchases for Large Stockholder

國內文獻指出，公司大股東（通常也是企業負責人）護盤的主要原因是避免質押在授信機構的股票被斷頭賣出。這個理由無法解釋為何沒有過度使用財務槓桿的大股東也會在公司利空消息傳出時買入公司股票。本文研究此類型大股東的護盤動機。本研究發現，大股東護盤需要成本，但護盤也降低股價波動使得公司股票享有較高的市場價格。本研究也發現在某些情形下（例如，大股東持有較多數量的公司股票，投資人的風險趨避程度較高，或股票的每人平均供給較大），大股東有較強的護盤動機；反之，在另外情形下（例如，利空消息證實為真的機率較大、護盤買入的股票數量較多、或利空消息引起價格下跌幅度較大），大股東護盤動機較低。

Many domestic studies declared that for large stockholder of a firm (also to be chief manager of the firm), the primary reason to execute open market share repurchases is to protect his mortgaged property of stocks. However, this reason is unable to explain why those large stockholders that have less financial leverage may also choose to execute share repurchases whenever there is a bad news concerned with the firm appeared. Our analysis finds that although the act to execute share repurchases may bring large stockholder some expenses, this action can on the other hand decrease stock volatility and therefore raise the stock price levels of the firm. The analysis also finds that when there is the situation such as: large stockholder possessing his firm’s stocks with comparatively large amount, investors showing fairly high degree of risk aversion, or the average number of stock supplies for each investor to be relatively large, the large stockholder has a stronger motive to execute open market share repurchases; on the contrary, under the situation such as: the probability of confirming the news to be bad being fairly high, the share repurchases needing to buy a comparatively large amount of stocks, or the bad news resulting price falling being relatively large, the large stockholder has less motive to execute share repurchases.