Abstract - Economics Research Reports


Modeling Stock Volatility with Trading Information

By Huirong Li (University of Western Ontario) and Jian Yang (University of Western Ontario)

January, 1999

This paper studies volatility in individual stocks of the Toronto Stock Exchange (TSE), using a recently developed nonlinear approach, a stochastic threshold model. Trading information is embedded into the determination process for volatility in the stochastic threshold model with a generalized conditional heteroskeasticitic variance (STGARCH). We use the number of price changes (quote changes) to approximate the trading information. This trading variable has significantly positive impact on stock volatility following a declining market and ambiguous impact on the stock volatility following a rising market; there is higher probability to fall into a highly volatile state after a declining market than after a rising market. The GARCH-type persistence in volatility is reduced significantly in our nonlinear model for individual stocks with high persistence. The STGARCH model also gives satisfactory fitting in terms of alternative model selection criteria.

JEL Classification: G12; C22
Keywords: volatility; asymmetry; trading variable; information arrivals; stochastic threshold