本文的主旨在於運用門檻迴歸模型與GJR-GARCH的模式，探 討在2007-2009年美國的次級房貸危機發生前後，美國股市中落遲 的交易額因子對於股市的隱含波動指數是否存在有非對稱性的影 響，或門檻效應；同時檢測隱含波動指數的條件變異數是否存在 有波動不對稱性的現象。本文主要的實證發現為：採用門檻模型 與GJR-GARCH的模式，發現在次貸危機發生前後，S&P 500指數 及NASDAQ指數的交易額落遲因子，對VIX及VXN兩個隱含波動 指數存在有顯著的門檻效應。該結果提供了顯著證據確認了之前 學者們所提出的連續訊息到達假說（Sequential Information Arrival Hypothesis, SIAH）；同時，實證結果亦發現VIX及VXN兩個隱含 波動指數的條件變異數，於次貸危機前後階段皆存在有波動不對 稱性的現象。

This article investigated whether the threshold effects existed in the relations between the lagged trading volume factors in equity markets and the implied volatility indices, and whether the volatility asymmetric effects existed in the conditional variances of the implied volatility indices in the U.S. markets around the Subprime Mortgage Crisis during 2007-2009. The main empirical findings demonstrated that, with the application the threshold model with the GJR-GARCH process, there were significant threshold effects from the lagged trading volume factors in the indices of S&P 500 and NASDAQ to the implied volatility indices of VIX and VXN around the Subprime Mortgage Crisis, our empirical results provide strong evidence to confirm the sequential information arrival hypothesis (SIAH). Moreover, the volatility asymmetries existed in the conditional variances of VIX and VXN in both periods of pre- and during the Subprime Mortgage Crisis.