abstract: Although margin trading has significant impacts on the stock market, extant research has mainly focused on its effect on stock price volatility and has rarely examined its influence on the rate of returns. In addition, little systematic research has examined the differential effects of margin trading under different circumstances. This thesis examines the effects of margin trading in bull market, bear market, balanced market and among stocks included in main board, SMEs(small and medium-sized enterprises) board, GEM(growth enterprises board), as well as large-cap and small-cap in China. I further studied the long-, medium-, and short-term influences of margin trading on the volatility of stock price, return rate, and liquidity of the market by both using the SVAR model and conducting panel data analyses. The findings show that: a)Volatility. Margin trading can effectively curtail the medium- and short-term volatility of the share price under any market condition but has no prominent influence on long-term volatility. b)Profitability. Margin trading enhances profitability in the bull market with an apparent leverage effect while having no significant effects on short-term profitability in the balanced market and the bear market. c) Individual shares with different attributes. The influences of margin trading on the large-cap and small-cap shares, shares with high vs. low PE ratio, shares included in the main board and SMEs stocks vary in different types of market. d) Liquidity. The influences of margin trading on the fluidity of market are significantly different in the bull, bear, and balanced markets. Finally, I set up a new trading strategy based on the above conclusions. The result from hypothetical trading demonstrates that the newly-created trading strategy works better than the long-term holding strategy, highlighting the practical implications of this thesis in addition to its implications for research / Dissertation/Thesis / Doctoral Dissertation Business Administration 2018

隨著台灣股票市場的自由化與國際化，信用交易與外資在台股的交易比重不斷的增加。本文旨在探討股價指數、信用交易指標之融資餘額與外資之關連性，利用Johansen共整合向量分析與誤差修正模型，以日資料進行實證分析研究，樣本期間為1998年1月2日起自2003年6月30日止，共1419個樣本觀測值。本研究結果如下：一、第t期的融資餘額與第t-2期的股價指數共整合程度最高，顯示股價指數領先融資餘額兩期，為其領先指標。二、同期的股價指數與外資持股共整合程度最高，且股價指數會受到前一期外資持股變量的影響，顯示外資在市場上的動作的確會造成其他投資人的跟進。三、同期的融資餘額與外資持股共整合程度最高，顯示兩者呈現同方向的變動，且外資持股會受到融資餘額前一期變量的影響，且方向相反。 / This paper examines the relationship between stock index, balance of margin trading, and stock holding of foreign investors. Using daily data from January 2 1998 through June 30 2003 we investigate the interactions among the three variables through Johansen cointegration analysis and error correction model. It is found that (1) balance of margin trading of time t and stock index of time t-2 have the highest level of cointegration, which means stock index leads the balance of margin trading for two days. (2) stock index and stock holding of foreign investors of the same time t have the highest level of cointegration, and stock index of time t is affected by the stock holding of foreign investors of time t-1. (3) balance of margin trading and stock holding of the same time t have the highest level of cointegration, and the stock holding of foreign investors at time t is adversely influenced by balance of margin trading of time t-1.

中國大陸進行改革開放以來，已成為外資的主要投資地區，在上海證券交易所及深圳證券交易所掛牌的股票市值，近年來於世界交易所組織的排名有顯著的上升。而中國大陸在2010年3月31日推出的有價證券融資融券制度（又稱信用交易），雖然在先進的證券市場中，融資融券係成熟的交易制度，但在中國大陸推出後卻產生交易量極不活絡、無券可融、控管過嚴等問題。 本文嘗試著先行介紹融資融券交易的沿革、定義、美國及台灣管理的模式，進而剖析探討中國大陸融資融券交易的開戶條件、證券商資格標準、有價證券得為融資融券標準、保證金帳戶制度、擬籌設的證券金融公司制度、風險管理制度、賣空監管制度、融資融券之法律關係等，作為本文之主軸。 全文共分五章，除於第一章說明本文之研究動機與目的、研究範圍與內容外，分別介紹證券市場信用交易之概述、中國大陸信用交易法令規範、融資融券交易之法律行為及實務作業探討，作為第二章至第四章之內容，最後於第五章提出檢討及建議，俾作為中國大陸融資融券交易法制之研究。 / Using the comparative law approach and the economics ananysis of law approach, this thesis studied securities law of margin trading in Mainland China. The margin trading mechanism was established in the Article 142 Securities Act 2005, and began on 31st Jan. 2010. This thesis first studied the definition, history and structure of margin trading. Then, by deploying economic analysis of law approach, it studied the margin trading rules of U.S, Taiwan and Mainland China in a comparatively way. Material issues were researched in the thesis: cash account, margin account, initial margin requirements, minimum maintenance requirements, securities lending, securities financing corporations, segregation of customer’s securities, short sale regulations, and guarantees. Based on above, this thesis reviewed the margin trading rules in Mainland China through legal, administrative, and market aspects. Finally, we proposed reform suggestions of the margin trading rules in Mainland China.

本研究主要探討兩項關於融券交易的議題。首先，本研究發現巨量融券與續後的股價反應呈現顯著的負相關。再者，進一步探究盈餘宣告前的融券信用交易是否與非盈餘宣告的時間存有差異。本研究是採用在台灣證券交易所上市之股票並觀察其盈餘宣告前五日之融券交易行為。實證結果發現盈餘宣告前的融券與盈餘宣告後的股價反應存在負向關係，顯示可能有私有資訊的交易者在盈餘宣告前進行融券交易。接下來本研究進一步使用基本財務比率中的帳面價值對市價比將樣本區分成價值型與成長型之股票，發現擁有較低比率之公司較受融券交易者之青睞。本研究希望研究成果能對證券市場主管機關在制訂法律與提供更即時、更廣泛的信用交易資訊揭露給投資大眾參考。 / This research examines two issues of short-selling transactions.First,we find a strong negative relationship between short interest and subsequent abnormal returns.The second is whether short-selling in the days leading up to an announcement differs from short-selling in times when no announcement is imminent.We examine short-selling behavior of investors in the five days prior to the earnings announcements of Taiwan Stock Exchange (TSE)listed firms.The tests provide evidence that there might exist informed trading in pre-announcement short-selling because they reveal that abnormal short-selling is significantly linked to post-announcement stock returns.A high level of unusual pre-announcement short-selling is an indicator of future stock returns at earnings announcement.Also,the tests indicate that short-sellers typically are more active in stocks with low book-to-market ratio valuation.We believe that these results should encourage financial market regulators to consider providing more extensive and timely disclosures of short-selling to investors.