A threshold model for Australian Stock Exchange equities

In this paper, we present a threshold model to describe the phenomena of zero return enhancement that is present in Australian Stock Exchange data. We examine the intraday behaviour of the ASX data and construct a new measure for the market activity using principal component analysis. We use this measure to create a business time scale that keeps the level of zero return enhancement constant throughout trading hours. Operating in this new time scale we fit the model to data for small and large time scales and find that the model affords an excellent approximation of the distribution of stock returns.