A simple estimate of noise and its determinant in a call auction market

This paper proposes a simple method to decompose the variance of returns into noise and information components, while allowing the two components correlated. To apply the method, this paper examines noise in the Taiwan Stock Exchange, which is a call auction market. It also studies the determinants of noise. It finds that noise has a distinct diurnal effect: the transaction price is less noisy at the open, but is noisier near the close. Trading mechanisms also affect noise: a larger relative tick size and a longer time interval increase noise. We also find that individual investors help to reduce noise.