本文探討在2006年到2012年期間，在台灣50指數成分股公司進行賣空交易對價格效率性的影響。本研究使用三種衡量價格效率性的指標，並依交易者類型將賣空交易分為一般投資人的融券賣出與機構法人的借券賣出。實證結果發現機構法人為有資訊的交易者，當機構法人進行愈多的借券賣出，將促使股價回到基本價值，也就是價格更有效率性；然而，一般投資人進行融券賣出並沒有顯著提升價格效率性。此外，當投資人對大型股進行賣空，將有助於降低股價的分歧程度，使得價格更有效率性，而投資人的交易成本愈低時，也有助於提升價格效率性。

This thesis explores the impact of short selling on price efficiency for the compositions of Taiwan 50 Index during the period from 2006 to 2012.This study uses three indicators to measure price efficiency, and short selling is divided into general investor’s short selling and institutional investor’s short selling according to different type of the traders. The empirical results show that institutional investors are informed traders. When institutional investors take more short selling, it will facilitate stock price return to fundamental value. In other words, the price is more efficient. However, general investors take short selling do not significantly improve price efficiency. In addition, when investors take short selling for large stocks, it will help to reduce the extent of price discreteness, making the price more efficient; when the transaction costs are lower, it will help to enhance price efficiency.

英文文獻
1.Asquith, P., Pathak, P. A., Ritter, J. R., 2005. Short interest, institutional ownership, and stock returns. Journal of Financial Economics 78, 243-276.
2.Basu, S., 1983. The relationship between earnings' yield, market value and return for NYSE common stocks: Further evidence. Journal of financial economics12, 129-156.
3.Beber, A., Pagano, M., 2013. Short‐Selling Bans Around the World: Evidence from the 2007–09 Crisis. The Journal of Finance 68, 343-381.
4.Boehme, R. D., Danielsen, B. R., Sorescu, S. M., 2006. Short-sale constraints, differences of opinion, and overvaluation. Journal of Financial and Quantitative Analysis 41, 455-487.
5.Boehmer, E., Jones, C. M., Zhang, X., 2008. Which shorts are informed?.The Journal of Finance 63, 491-527.
6.Boehmer, E., Jones, C. M., Zhang, X., 2013. Shackling short sellers: The 2008 shorting ban. Review of Financial Studies 26, 1363-1400.
7.Boehmer, E., Wu, J. J., 2013. Short selling and the price discovery process. Review of Financial Studies 26, 287-322.
8.Bris, A., Goetzmann, W. N., Zhu, N., 2007. Efficiency and the bear: Short sales and markets around the world. The Journal of Finance 62, 1029-1079.
9.Carhart, M. M., 1997. On persistence in mutual fund performance. The Journal of finance 52, 57-82.
10.Chang, E. C., Cheng, J. W., Yu, Y., 2007. Short‐sales constraints and price discovery: Evidence from the Hong Kong market. The Journal of Finance 62, 2097-2121.
11.Dechow, P. M., Hutton, A. P., Meulbroek, L., Sloan, R. G., 2001. Short-sellers, fundamental analysis, and stock returns. Journal of Financial Economics 61, 77-106.
12.Desai, H., Ramesh, K., Thiagarajan, S. R., Balachandran, B. V., 2002. An investigation of the informational role of short interest in the Nasdaq market. The Journal of Finance 57, 2263-2287.
13.Diamond, D. W., Verrecchia, R. E., 1987. Constraints on short-selling and asset price adjustment to private information. Journal of Financial Economics 18, 277-311.
14.Diether, K. B., Lee, K. H., Werner, I. M., 2009. Short-sale strategies and return predictability. Review of Financial Studies 22, 575-607.
15.Fama, E. F., & French, K. R., 1992. The cross‐section of expected stock returns. the Journal of Finance47, 427-465.
16.Fama, E. F., MacBeth, J. D., 1973. Risk, return, and equilibrium: Empirical tests. The Journal of Political Economy 607-636.
17.Hasbrouck, J., 1993. Assessing the quality of a security market: A new approach to transaction-cost measurement. Review of Financial Studies 6, 191-212.
18.Hong, H., Stein, J. C., 2003. Differences of opinion, short‐sales constraints, and market crashes. Review of financial studies 16, 487-525.
19.Hou, K., Moskowitz, T. J., 2005. Market frictions, price delay, and the cross-section of expected returns. Review of Financial Studies 18, 981-1020.
20.Jones, C. M., Lamont, O. A., 2002. Short-sale constraints and stock returns.Journal of Financial Economics 66, 207-239.
21.Karpoff, J. M., Lou, X., 2010. Short sellers and financial misconduct. The Journal of Finance 65, 1879-1913.
22.Lakonishok, J., Shleifer, A., Vishny, R. W., 1994. Contrarian investment, extrapolation, and risk. The journal of finance 49, 1541-1578.
23.Miller, E. M., 1977. Risk, uncertainty, and divergence of opinion. The Journal of Finance 32, 1151-1168.
24.Newey, W. K., West, K. D., 1987. Hypothesis testing with efficient method of moments estimation. International Economic Review 777-787.
25.Saffi, P. A., Sigurdsson, K., 2011. Price efficiency and short selling. Review of Financial Studies 24, 821-852.
26.Seneca, J.J., 1967. "Short interest: bearish or bullish?" Journal of Finance 22, 67-70.
27.Stattman, D., 1980. Book values and stock returns. The Chicago MBA: A journal of selected papers4, 25-45.
中文文獻
1.柯如鳳(2006)，「豁免融券賣出不得低於前一營業日收盤價對市場品質之影響-以臺灣50指數成分股為例」，國立中央大學財務金融研究所碩士論文。
2.張琬蕎(2010)，「取消平盤放空限制對台灣中型100指數成分股流動性、波動性與效率性之影響」，逢甲大學財務金融研究所碩士論文。
3.黃致遠(2010)，「法人與散戶賣空之動機及其對股票報酬影響之探討」，國立中山大學財務管理研究所碩士論文。
4.陳家懿(2012)，「借券賣出與股價報酬率之實證研究」，國立中央大學財務金融研究所碩士論文。
5.陳旻暄(2013)，「賣空交易對股價報酬率影響之實證研究」，國立中央大學財務金融研究所碩士論文。
中文書籍
1.鍾惠民等編著，財金計量，雙葉書廊，台北市，2002年。
2.周賓凰，計量經濟學：理論、觀念與應用，智勝文化，台北市，2010年。
3.彭昭英、唐麗英主編，SAS123，七版，儒林圖書，台北市，2010年。