Apparaît dans la collection : COSA : Interactions in applied mathematics for economics, finance and Insurance / Interactions en mathématiques appliquées à l'économie, la finance et l'assurance
We propose a microstructural model for the order flow in financial markets that distinguishes between core orders and reaction flow, both modeled as Hawkes processes. This model has a natural scaling limit that reconciles a number of salient empirical properties: persistent signed order flow, rough trading volume and volatility, and power-law market impact.
In our framework, all these quantities are pinned down by a single statistic H0, which measures the persistence of the core flow. Specifically, the signed flow converges to the sum of a fractional process with Hurst index H0 and a martingale, while the limiting traded volume is a rough process with Hurst index H0 − 1/2.
No-arbitrage constraints imply that volatility is rough, with Hurst parameter 2H0 − 3/2, and that the price impact of trades follows a power law with exponent 2 − 2H0. The analysis of signed order flow data yields an estimate H0 close to 3/4.