台灣股市收盤資訊揭露制度與價格效率的關聯性

台灣股市過去在收盤5分鐘的集合競價階段並未揭露任何買賣資訊，導致最後收盤價可能與前一盤有所差距，亦即尾盤容易發生作價的情形。自2012年2月20日開始實施新的收盤揭示制度，收盤最後5分鐘每隔20秒，揭露模擬撮合後之最佳1檔買賣價格，同時也實施配套措施－個股收盤最後1分鐘漲跌幅超過3.5%時，暫緩2分鐘收盤。本文以台灣股市為研究對象，探討收盤資訊揭露制度與價格效率的關聯性。研究發現，尾盤透明度提升可以改善價格發現過程，不僅降低報酬波動，同時也增加價格的資訊效率性。更重要的是，新制在防止尾盤刻意拉抬或摜壓價格的成效，會隨個股規模而有所不同，對於中小型股而言，新制確實可以減少最後一盤人為作價的情形，但權值股尾盤作價並無顯著降低，大型股的期貨『結算行情』不受影響，同時也出現提前作價的傾向。

關鍵字

市場透明度；尾盤人為作價；價格效率

並列摘要

This paper examines price efficiency responding to the new rule posted by the Taiwan Stock Exchange (TSE), effective on 2/20/2012. To improve price efficiency, TSE has revised the rule of the closing session, starting from five minutes before the close, wherein real trades are replaced with a sequence of simulated call auctions. The best quotes and the indicative trading prices are disseminated on line, instead of ＂trading in dark＂ as before. If a stock’s final simulated price deviates from the previous trading price by 3.5%, the stock’s final auction will be postponed by two minutes. Evidence shows that the rising transparency overall improves price efficiency by lowering price volatility. More importantly, the improvement varies with firm size. That for small- and medium-cap stocks is more pronounced than that for large-cap stocks, tightly linked to the index futures. No obvious expiration-day effect on large-cap stocks exists; and price manipulations on them shift ahead of the closing session.

並列關鍵字

transparency ； closing price manipulation ； price efficiency

參考文獻

林雅玲、馬黛、陳秀桂(2011)。透明度、資訊內涵及下單策略之實證研究。財務金融季刊。19(1)，1-32。

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Hendershott, T. and C. M. Jones, 2003. Island Goes Dark: Transparency, Fragmentation, Liquidity Externalities, and Multimarket Regulation, working paper, University of California.

Google Scholar

Kang, J. and D. Lee, 2007. The Effect of a Transparency Change in the Pre-opening Session on Price Discovery, Working paper, KAIST Graduate school of business.