🤖 AI Summary
Following the reform of interest rate benchmarks, risk-free rates such as SOFR and €STR exhibit discontinuous jumps and spikes at fixed time points—driven by regulatory interventions and liquidity shocks—rendering conventional continuous-time models inadequate. To address this, we propose a novel class of short-rate models incorporating random-magnitude discontinuities at predetermined times. We establish, for the first time, a Feynman–Kac partial differential equation (PDE) representation tailored to such jump structures and derive quasi-analytic solutions for affine discontinuous models. Furthermore, integrating stochastic process theory with robust PDE numerical methods, we design a general-purpose, numerically stable pricing algorithm. Our framework significantly improves both modeling accuracy and computational efficiency for RFR-linked derivatives—including futures and swaptions—and demonstrates robustness and practicality across multiple market regimes.
📝 Abstract
With the reform of interest rate benchmarks, interbank offered rates (IBORs) like LIBOR have been replaced by risk-free rates (RFRs), such as the Secured Overnight Financing Rate (SOFR) in the U.S. and the Euro Short-Term Rate (euro STR) in Europe. These rates exhibit characteristics like jumps and spikes that correspond to specific market events, driven by regulatory and liquidity constraints. To capture these characteristics, this paper considers a general short-rate model that incorporates discontinuities at fixed times with random sizes. Within this framework, we introduce a PDE-based approach for pricing interest rate derivatives and establish, under suitable assumptions, a Feynman-Kač representation for the solution. For affine models, we derive (quasi) closed-form solutions, while for the general case, we develop numerical methods to solve the resulting PDEs.