Navigating the architecture of overnight jumps: a t-stable power series approach to information shocks and market resilience
摘要
Opening price gaps provide an observable measure of how information released outside regular trading hours is incorporated into the first tradable price of the next session. Their empirical distributions often display heavy tails, mild asymmetry, and clustered extreme movements, which are difficult to describe using benchmark distributions based on a single regime structure. This study introduces the t-stable power series (TSPS) distribution as a parametric framework for modelling opening gap rates, referred to as opening diffrates, and overnight tail risk. The model combines a Student-t equilibrium component with a stable power series (SPS) shock component, allowing regular price discovery movements to be separated from random sum information shocks. This structure yields an interpretable decomposition of overnight risk through three quantities: the probability of the shock regime, the tail thickness of individual shock impacts, and the latent frequency of material information arrivals. We apply the framework to opening diffrates of major equity indices, including the Shanghai Composite, S&P 500, DAX, and Nikkei 225, and compare it with Normal, Laplace, Cauchy, Student-t, and