Matteo Ferrari, Roger J. A. Laeven, Emanuela Rosazza Gianin, Marco Zullino · 2026-06-29
The paper extends an existing idea of a 'resilience rate' — how fast a financial position recovers or worsens after adverse moves — by measuring not just the expected change but the risk profile of that change using a dynamic (possibly nonlinear) convex risk measure. For Itô-process price dynamics and risk measures defined via backward stochastic differential equations, it proves the resulting 'resilience evaluation' is well-defined and derives an explicit formula, expressed as a worst-case expected effective drift that blends the position's drift with a risk adjustment on its volatility.
Why it matters: The work offers a more refined mathematical lens for assessing how a position responds to stress, distinguishing between holdings with equal expected recovery but different downside risk. In principle this could inform risk-management frameworks that care about resilience and tail behavior, not just average returns, though it remains a theoretical construction.
⚠ This is a purely theoretical, mathematical result with no empirical testing, backtest, or demonstrated trading application.
Financial resilience concerns the rate at which a position recovers, or further deteriorates, in response to adverse conditions. As a first step, Laeven, Ferrari, Rosazza Gianin, and Zullino (arXiv:2505.07502) introduced the resilience rate, defined as the expected instantaneous rate of (favorable) change of a price or risk-assessment process. Since this quantity captures only the conditional mean of future increments, it cannot distinguish between positions having the same expected recovery but different conditional risk profiles. We obtain a richer characterization by evaluating such increments through a genuine, possibly nonlinear, dynamic risk measure. More precisely, for an Itô process $π$ and a normalized, cash-additive dynamic risk measure $ρ$, we define the resilience evaluation by \[\mathcal D_s^ρπ_t := L^1\text{-}\lim_{\varepsilon\to0^+} \frac{1}{\varepsilon}ρ_s(π_{t+\varepsilon}-π_t), \qquad 0\leq s\leq t<T,\] whenever the limit exists. When $ρ$ is a convex dynamic risk measure induced by a BSDE with a Lipschitz or quadratic driver, we prove that this limit is well-posed and admits an explicit dual representation. It is given by the worst-case conditional expectation, over a zero-penalty class of measure changes, of an effective drift combining the drift of $π$ with the risk adjustment assigned by $ρ$ to its volatility. We further establish attainment of the optimal scenario and illustrate the scope of the construction, as well as the role of the assumptions, through examples and counterexamples.
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