Information-Theoretic Approach to Financial Market Modelling
Eckhard Platen
TL;DR
The paper reframes financial markets as information channels and derives a parsimonious minimal market model (MMM) from four information-theoretic assumptions. State variables are scalar stationary diffusions whose normalized factors and growth-optimal portfolio follow squared radial Ornstein-Uhlenbeck processes in market time, with a single governing parameter $\hat{\lambda}$. It shows that surprisal minimization yields gamma stationary densities for normalized factors with dof $d_k=4\omega^k$ and equal factor weights $\omega^k=1/n$, and that information minimization produces a benchmark-time diffusion of dimension four and constant $\hat{\lambda}$, enabling benchmark-neutral pricing via an equivalent BN measure $Q_{S^*}$. Empirically, MMM captures key stylized facts such as stationary volatility, four-degree-of-freedom Student-$t$ log-returns, leverage effects, and rough/3/2 volatility, while producing accurate hedges for inexpensive long-dated bonds and providing a practical, information-theoretic foundation for pricing and hedging in finance.
Abstract
The paper treats the financial market as a communication system, using four information-theoretic assumptions to derive an idealized model with only one parameter. State variables are scalar stationary diffusions. The model minimizes the surprisal of the market and the Kullback-Leibler divergence between the benchmark-neutral pricing measure and the real-world probability measure. The state variables, their sums, and the growth optimal portfolio of the stocks evolve as squared radial Ornstein-Uhlenbeck processes in respective activity times.
