所謂私募，即是企業能針對特定的法人機構或符合一定資格的自然人發行有價證券，籌募資金。過去的研究顯示，公司在發行私募股權之後，長期股價表現會呈現負向變動，而Hertzel, Lemmon, Linck, and Rees (2002)認為此一現象的產生可能與內部關係人的交易行為有關。意即，當公司的市場價值被高估時，經理人會利用私募方式賣出其所持有的股票，而此行為造成私募公司長期股價反應為負。但此一說法在過去的文獻中從來沒有被證實過。因此在本研究中，我將透過內部關係人的交易行為來檢定視窗機會假說(window of opportunity)。視窗機會假說預測，內部關係人在私募宣告前，可能會賣出其所持有的股票，而從所賣出的數量，可以預測私募公司的長期績效表現。若公司內部關係人賣得愈多，則公司長期績效反應應該愈不好。

　　經過實證，本篇研究支持機會視窗假說。透過回歸分析，發現私募公司長期股價表現與淨買次數、異常淨買次數、淨買股數、異常淨買股數、淨買金額量、及異常淨買金額顯著呈現正向關係，此表示，內部關係人若在私募發行前進行賣的交易愈頻繁、賣的股數數量愈多、或是賣的金額量愈大，則私募公司長期的績效反應愈差。

　A private placement is a transaction by an issuer committed to selling all new issues to investors without general solicitation of public ones. Prior empirical evidence suggested that private placement firms experience negative post-announcement stock-price performance. Hertzel, Lemmon, Linck, and Rees (2002) argue that insider trading could be one explanation of this scenario. That is, mangers may knowingly sell shares privately when the equity is overvalued in the market, and this leads to the negative long-run performance. Though, this argument has never been examined in the literature. So in this study, I test the “window of opportunity” hypothesis by examining insider trading activities. The “window of opportunity” hypothesis predicts that insiders may sell their holdings of equity before private placement, and the amount of sales can predict the long-run performance of private placement firms. Usually, the more the insiders sell, the worse the long-run performance will be.

　My results support the “window of opportunity” hypothesis. In all the regressions I conduct, the stock returns are significantly positively related to number of net purchases, abnormal number of net purchases, shares of net purchases, abnormal shares of net purchases, dollar value of net purchases, and abnormal dollar value of net purchases. This evidence indicates that the more the insiders sell prior to the private placement issuing, the worse the long-run stock-price performance will be.

Arshadi, N. and T. H. Eyssell, 1991, "Regulatory deterrence and registered insider trading: the case of tender offers”, Financial Management, 20, 30-39.
Barclay, M. J., C. G. Holderness, and D.P. Sheehan, 2001, “The block pricing puzzle", Working Paper, University of Rochester.
Barclay, M. J., C. G. Holderness, and D. P. Sheehan, 2003, “Private placement and managerial entrenchment”, Working Paper, AFA 2004 San Diego Meetings.
Clarke, J., C. Dunbar, and K. M. Kahle, 2001, “Long-run performance and insider trading on completed and canceled seasoned equity offerings", Journal of Financial and Quantitative Analysis, 36, 415-430.
Gombola, M., H. W. Lee, and F. Y. Liu, 1997, “Evidence of selling by managers after seasoned equity offering announcements”, Financial Management, 26, 37-53.
Cronqvist, H., M. Nilsson, 2003, “The choice between rights offerings and private equity placements”, Working Paper, University of Chicago.
Hertzel, M. and R. L. Smith, 1993, “Market discounts and shareholder gains for placing equity privately”, Journal of Finance, 48, 459-485.
Hertzel, M., M. Lemmon, J. S. Linck, and L.Rees, 2002, “Long-run performance following private placements of equity”, Journal of Finance, 57, 2595-2617.
Lee, I., 1997, “Do firms knowingly sell overvalued equity?” Journal of Finance, 52, 1439-1466.
Irani, A. J., 2003, “Management earnings forecast bias and insider trading: comparison of distressed and non-distressed firms”, Journal of Business & Economics Studies, 9, 12-25.
Krishnamurthy, S., P. Spindt, V. Subramaniam, and T. Woidtke, 1999, ”Do shareholders gain from a private placement? The role of information
asymmetry, monitoring, and wealth transfer”, Working Paper, Tulane University.
Krishnamurthy, S., P. Spindt, V. Subramaniam, and T. Woidtke, 2003, “Does investor identity matter in equity issues? Evidence from private placement”, Forthcoming, Journal of Financial Intermediation.
Lee, D. S., W. H. Mikkelson, and M. M. Partch, 1992, “Managers’ trading around stock repurchases”, Journal of Finance, 47, 1947-1961.
Pettit, R. R., and P. C. Vankatesh, 1995, “Insider trading and long-run return performance”, Financial Management, 24, 88-103.
Prowse, S. D., 1998, ”The economics of the private equity market”, Economics Review – Federal Reserve Bank of Dallas, Third Quarter 1998, 21-34.
Sheehan, D. P. and J. Swisher, 1998, “How sophisticated are “sophisticated”investors?” Working Paper, Pennsylvania State University.
Wruck, K. H., 1989, “Equity ownership concentration and firm value: evidence from private equity financings”, Journal of Financial Economics, 23, 3-28.
Wu, YiLin., 2000, “The choice between public and private equity offerings”, Working Paper, University of Chicago.
Wu, YiLin., 2001, “Using insider trading to infer the information content of equity-selling mechanisms”, Working Paper, Hong Kong University.