Stochastic Volterra equations: failure of the time-homogeneous Markov property

Path-dependence is a defining feature of many real-world systems, with applications ranging from population dynamics to rough volatility models and electricity spot prices.

In stochastic Volterra equations (SVEs), such dependence is encoded in the Volterra kernel, which dictates how past trajectories influence present dynamics on infinitesimal time scales.

This structure suggests a breakdown of the Markov property.

In this article, we develop computational techniques and methods based on small-time asymptotics for SVEs with Hölder coefficients to rigorously establish that they cannot possess the time-homogeneous Markov property.

In particular, for affine drifts, we characterise the time-homogeneous Markov property and show that under natural non-degeneracy conditions, it only holds for exponential Volterra kernels.