香港證券交易所於2002年3月25日，制定開盤前時段的新交易安排，目的是為了提高市場運作效率。本文之目的，為檢驗開盤前委託簿資訊透明度增加後，對於市場流動性及價格效率的影響。
  市場流動性方面，是以價差和市場深度來衡量。實證結果首先指出日內價差型態為J型，深度則為反J型；其次，在市場透明度提高後，整體價差顯著地變寬，同時也發現價差會隨著交易活動程度的增加而變窄；進一步從價差分解的結果得知，交易活動程度高的組合樣本，其不對稱訊息成本佔隱含價差的比例顯著減少，表示在揭露開盤前時段委託簿的資訊後，活動程度高的投資者更願意下單，而交易活動程度低的交易者，因為透明度增加後，更不容易成交，使得流動性成本顯著增加，進而加大了價差寬度。
  價格發現方面，是以買賣價中點報酬所反映的資訊量來衡量，實證結果指出，報酬中所包含的資訊會隨著交易過程的進行而逐漸增加，雜訊則會逐漸減少，所以在價格發現的過程中，均衡價格具有學習效果，價格效率在新的交易機制下可以充份發揮。

On March 25, 2002, Stock Exchange of Hong Kong introduces a new arrangement of extending trading session before open. The purpose of this study is to examine the impact of increasing transparency on bid-ask spreads, market depth, and price efficiency. The empirical results suggest that the intraday variations in spread display similarly J-shaped patterns, but the market depth shows a reverse J-shaped pattern. We also find that dollar and percentage quoted spread significant decrease as the trading activity increases. With the finding that wider spread after the new introduction, we suggest the asymmetric information component of spread may increase significantly following the open limit book of preopening trading session. The measurement of the amount of price discovery during preopening increases as the trading activity increases. Final, we also show in the context of price discovery process that the continuously increasing of the estimated slope of unbiasedness regression consists with more information incorporated into the price through the trading process.

Abstract in Chinese：	i
Abstract in English：	ii
List of Tables	iv
List of Figures	v
Chapter 1	Introduction	1
Chapter 2	Market Structure	8
2.1.	Trading mechanism	8
2.2.	Data	10
2.3.	Descriptive statistics	12
Chapter 3	Liquidity and Transparency	19
3.1	Introduction	19
3.2	Liquidity measurements	24
3.3	Hypotheses framework	30
3.4	Components of spread	44
Chapter 4	Price Discovery During the Preopening Period	51
4.1	Introduction	51
4.2	Descriptive statistics	54
4.3	Price discovery	57
Chapter 5	Conclusions	66
Reference	69

List of Tables

Table 2.1 Descriptive statistics	14
Table 3.1 Descriptive statistics	28
Table 3.2 Regression models for the relationship between depth and spread	36
Table 3.3 Changes in spread surrounding the event date	39
Table 3.4 Regression models for spreads	42
Table 3.5 Transition cost component of spread	50
Table 4.1: Weighted price contribution from open to close	61

List of Figures

Figure 1.1 Layout of the thesis	7
Figure 2.1 Distribution of volume and return volatility	16
Figure 2.2 Distribution of number of trades	17
Figure 2.3 Distribution of trading volume	18
Figure 3.1 Time of day for the spread and depth	31
Figure 3.2 Time of day for the percentage of spread and depth	32
Figure 3.3 Time of day for the standardized variation	33
Figure 4.1 Time of day for the volume and volatility	55
Figure 4.2 Time of day for the percentage volume and trades	56
Figure 4.3 Time of day for the spreads	57
Figure 4.4 Time of day for the weighted price contribution	59
Figure 4.5 Distribution of WPC	62
Figure 4.6 Unbiasedness regressions	64
Figure 4.7 RMSE of the unbiasedness regression	65

Aggarwal, R. and Conroy, P., 2000, “Price Discovery in Initial Public Offerings and the Role of the Lead Underwriter,” Journal of Finance, 55, 2903-2922.
Ahn, H. J., Bae, K. H. and Chan, K., 2001, “Limit Orders, Depth, and Volatility: Evidence from the Stock Exchange of Hong Kong,” Journal of Finance, 56, 767-788.
Ahn, H. J. and Cheung, Y. L., 1999, “The Intraday Patterns of the Spread and Depth in a Market without Market Makers: The Stock Exchange of Hong Kong,” Pacific-Basin Finance Journal, 7, 539-556.
Amihud, Y. and Mendelson, H., 1987, “Trading Machanisms and Stock Returns: An Empirical Investigation,” Journal of Finance, 42, 533-553.
Amihud, Y. and Mendelson, H., 1991, “Volatility, Efficiency, and Trading: Evidence from the Japanese Stock Market,” Journal of Finance, 46, 1765-1789.
Bacidore, J. M. and Sofianos, G., 2002, “Liquidity Provision and Specialist Trading in NYSE-listed Non-U.S. Stocks,” Journal of Financial Economics, 63, 133-158.
Becker, B., Lopez, E., Berberi-Doumar, V., Cohn, R. and Adkins, A. S., 1993, “Automated Securities Trading,” Journal of Financial Services Research, 6, 327-341.
Barclay, M. J. and Hendershott, T., 2003, “Price Discovery and Trading after Hours,” Review of Financial Studies, 16, 1041-1073.
Barclay, M. J. and Hendershott, T., 2004, “Liquidity Externalities and Adverse Selection: Evidence from Trading after Hours,” Journal of Finance, 59, 681-710.
Barclay, M. J. and Hendershott, T., 2009, “A Comparison of Trading and Non-trading Mechanisms for Price Discovery,” Journal of Empirical Finance, 15, 839-849.
Barclay, M. J. and Warner, J. B., 1993, “Stealth Trading and Volatility : Which Trades Move Prices?” Journal of Financial Economics, 34, 281-305.
Baruch, S., 2005, “Who Benefits from an Open Limit-Order Book?” Journal of Business, 78, 1267–1306.
Biais, B., Hillion, P. and Spatt, C., 1999, “Price Discovery and Learning during the Preopening Period in the Paris Bourse,” Journal of Political Economy, 107, 1218-1248.
Bloomfield, R. and O’Hara, M., 1999,”Market Transparency: Who Wins and Who Loses,” Review of Financial Studies, 12, 5-35.
Bloomfield, R. and O’Hara, M., 2000, “Can Transparent Markets Survive?” Journal of Financial Economics, 55, 425-459.
Board, J. and Sutcliffe, C., 1996, “Trade Transparency and the London Stock Exchange,” European Financial Management, 2, 355-365.
Board, J. and Sutcliffe, C., 2000, “The Proof of the Pudding: the Effects of Increased Trade Transparency in the London Stock Exchange,” Journal of Business and Accounting, 27, 887-909.
Boehmer, E., Saar, G. and Yu, L., 2005, “Lifting the Veil: An Analysis of Pre-trade Transparency at the NYSE,” Journal of Finance, 60,783-815.
Brailsford, T. J., Frino, A., Hodgson, A. and West, A., 1999, “Stock Market Automation and the Transmission of Information between Spot and Futures Markets,” Journal of Multinational Financial Management, 9, 247-264.
Brockman, P. and Chung, D. Y., 1998, “Inter- and Intra-day Liquidity Patterns on the Stock Exchange of Hong Kong,” Journal of International Financial Markets, 8, 277-298.
Cao, C., Ghysels, E. and Hatheway, F., 2000, “Price Discovery without Trading: Evidence from the NASDAQ Preopening,” Journal of Finance, 55, 1339-1365.
Cao, C., Hansch, O. and Wang, X., 2009, “The Informational Content of an Open Limit Order Book,” Journal of Futures Markets, 29, 16-41.
Chen, C. H., Yu, W. C. and Zivot, E., 2009, “Prediction Stock Volatility After-Hours Information,” Working Paper, Available at SSRN http://ssrn.com/abstract=1324991.
Chen, T., Cai, J. and Ho, R.Y.K., 2009, “Intraday Information Efficiency on the Chinese Equity Market,” China Economic Review, 20, 527-541.
Christie, W. and Schultz, P., 1994, “Why do NASDAQ Market Makers Avoid Odd-Eighth Quotes?” Journal of Finance, 49, 1813-1840.
Chung, K. H. and Chuwonganant, C., 2009, “Transparency and Market Quality: Evidence from SuperMontage,” Journal of Financial Intermediation, 18, 93-111.
Chung, K. H. and Van Ness, R. A., 2001, “Order Handling Rules, Tick Size, and the Intraday Pattern of Bid-Ask Spreads for Nasdaq Stocks,” Journal of financial Markets, 4, 143-161.
Chung, K. H., Van Ness, B. F. and Van Ness, R.A., 1999, “Limit Orders and the Bid-Ask Spread,” Journal of Financial Economics, 53, 255-287.
Chung, K. H., and Zhao, X., 2003, “Intraday Variation in the Bid-Ask Spread: Evidence after the Market Reform,” Journal of Financial Research, 26, 191-206.
Comerton-Forde, Carole, Rydge, James and Burridge,Hayley, 2007, “Not All Call Auctions Are Created Equal: Evidence from Hong Kong,” Review of Quantitative Finance and Accounting, 29, 395-413.
Davies, R. J. 2003, “The Toronto Stock Exchange Preopening Session,” Journal of Financial Markets, 6, 491-516.
De Winne, R. and D'Hondt, C., 2005, “Market Transparency and Traders' Behavior: An Analysis on Euronext with Full Order Book Data,” Working Paper, Catholic University of Mons.
Ellis, K., Michaely, R. and O’Hara, M., 2000, “When the Underwriter Is the Market Maker: An Examination of Trading in the IPO Aftermarket,” Journal of Finance, 55, 1039-1074.
Fama, E. F. and MacBeth, J. D., 1973, “Risk, Return, and Equilibrium: Empirical Tests,” Journal of Political Economy, 81, 607-636.
Ferris, S. P., McInish, T. H. and Wood, R. A., 1997, “Automated Trade Execution and Trading Activity: The Case of the Vancouver Stock Exchange,” Journal of International Financial Markets, Institutions and Money, 7, 61-72.
Eom, K. S., Ok, J. and Park, J. H., 2007, “Pre-trade Transparency and Market Quality, Journal of Financial Markets, 10, 319-341.
Flood, M. D., Huisman, R. and Koedijk, K. G., and R. J. Mahieu, 1999, “Quote Disclosure and Price Discovery in Multi-Dealer Financial Markets,” Review of Financial Studies, 12, 37-59.
Gemmill, G., 1996, “Transparency and Liquidity: A Study of Block Transactions in the London Stock Exchange under Different Publication Rules,” Journal of Finance, 51, 1765-1790.
George, T. J., Kaul, G. and M. Nimalendran, 1991, “Estimation of the Bid-Ask Spread and Its Components: A New Approach,” Review of Financial Studies, 4, 623-656.
Glosten, L. and Harris, L., 1988, “Estimates of the Components of the Bid-Ask Spread,” Journal of Financial Economics, 21, 123-142.
Hansch, O., 2003, “Island Tides: Exploring ECN Liquidity,” Working Paper, Available at SSRN: http://ssrn.com/abstract=407705.
Harris, L. and Hasbrouck, J., 1996, “Market vs. Limit Orders: the SuperDot Evidence on Order Submission Strategy,” Journal of Financial and Quantitative Analysis, 31, 219-232.
Hasbrouck, J. and Schwartz, R. A., 1988, “Liquidity and execution costs in equity markets,” Journal of Portfolio Management, 14, 10-16.
Hasbrouck, J., 1991, “Measuring the Information Content of Stock Trades,” Journal of Finance, 46, 179-207.
Hauser, S., Shurki, I. and Kamara, A., 2009, “Market Design and the Efficiency of a Stock Market Under Liquidity Stress,” Working Paper, Available at SSRN: http://ssrn.com/abstract=1364451.
Hendershott, T. and Mendelson, H., 2000, ‘‘Crossing Networks and Dealer Markets: Competition and Performance,’’ Journal of Finance, 55, 2071–2115.
Hendershott, T. and Jones, C. M., 2005, “Island Goes Dark: Transparency, Fragmentation, and Regulation,” Review of Financial Studies, 18, 743-793.
Huang, R. D., 2002, “The Quality of ECN and Nasdaq Market Maker Quotes,” Journal of Finance, 57, 1285-1319.
Kalay, A., Sade, O. and Wohl, A., 2004, “Measuring Stock Illiquidity: An Investigation of the Demand and Supply Schedules at the Tel Aviv Stock Exchange,” Journal of Financial Economics, 74, 461-486.
Lee, C. M. C. and Ready, M. J, 1991, “Inferring Trade Direction from Intraday Data,” Journal of Finance, 42, 733-746.
Lyons, R. K., 1996, “Optimal Transparency in a Dealership Market with an Application to Foreign Exchange,” Journal of Financial Intermediation, 5, 225-254.
Madhavan, A., 1992, “Trading Mechanisms in Securities Markets,” Journal of Finance, 47, 607-642.
Madhavan, A., 1996, “Security Price and Market Transparency”, Journal of Financial Intermediation, 5, 255-283.
Madhavan, A. and Panchapageean, V., 2000, “Price Discovery in Auction Markets: A Look Inside the Black Box,” Review of Financial Studies, 13, 627-658.
Madhavan, A., Porter, D. and Weaver, D., 2005, “Should Securities Markets be Transparent?” Journal of Financial Markets, 8, 266-288.
Madhavan, A., Richardson M. and Roomans, M., 1997, “Why Do Security Prices Change? A Transaction-Level Analysis of NYSE Stocks,” Review of Financial Studies, 10, 1035-1064.
McInish, T. H., Van Ness, B.F. and Van Ness R. A., 1998, “The Effect of the SEC’s Order-handling Rules on Nasdaq,” Journal of Financial Research, 21, 3, 247-254.
McInish, T. H. and Wood, R. A., 1992, “An Analysis of Intraday Patterns in Bid/Ask Spreads for NYSE Stocks,” Journal of Finance, 47, 753-764.
Medrano, L. A. and Vives, X., 2001, “Strategic Behavior and Price Discovery,” Rand Journal of Economics, 32, 221-248.
O’Hara, M., 1995, Market Microstructure Theory, Basil Blackwell, Cambridge, Mass. 
Pagano, M. and Röell, A., 1990,“Shifting Gears: An Economic Evaluation of the Reform of the Paris Bourse,” Working Paper No. 103, London Stock Exchange Financial Markets Group, London School of Economics, London.
Pagano, M. and Röell, A., 1996, “Transparency and Liquidity: A Comparison of Auction and Dealer Markets with Informed Trading,” Journal of Finance, 51, 579-611.
Peiers, B., 1997, “Informed Traders, Intervention, and Price Leadership: A Deeper View of the Microstructure of the Foreign Exchange Market,” Journal of Finance, 52, 1589-1614.
Porter, D. C. and Weaver, D. G., 1998, “Post-trade Transparency on Nasdaq’s National Market System,” Journal of Financial Economics, 50, 231-252.
Rules of the Hong Kong Exchange, http://www.hkex.com.hk/eng/rulesreg/traderules /exrule.htm
Schwartz, R .A. and Weber, B. W., 1997, “Next-generation Securities Market Systems: An Experimental Investigation of Quote-driven and Order-driven Trading,” Journal of Management Information Systems, 14, 57-79.
Silva, A. C. and Chavez, G., 2002, “Components of execution costs: evidence of asymmetric information at the Mexican Stock Exchange,” Journal of International Financial Markets, Institutions and Money, 12, 253-278.
Simaan, Y., Weaver, D. G. and Whitcomb, D.K., “Market Maker Quotation Behavior and Pretrade Transparency,” 2003, Journal of Finance, 58, 1247-1267.
Venkataraman, K., 2001, “Automated Versus Floor Trading: An Analysis of Execution Costs on the Paris and New York Exchange,” Journal of Finance, 56, 1445-1485.
Vo, M. T., 2007, “Limit Orders and the Intraday Behavior of Market Liquidity: Evidence from the Toronto Stock Exchange, Global Finance Journal, 17, 379-396.
Weston, J. P., 2002, “Electronic Communication Networks and Liquidity on the Nasdaq,” Journal of Financial Service Research, 22, 125-139.
Zhao, X. and Chung, K. H., 2007, “Information Disclosure and Market Quality: The Effect of SEC Rule 605 on Trading Costs,” Journal of Financial and Quantitative Analysis, 42, 657-682.