Deep xVA solver -- A neural network based counterparty credit risk management framework

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Deep xVA solver -- A neural network based counterparty credit risk management framework

Alessandro Gnoatto
Athena Picarelli
Christoph Reisinger
Published on 5/6/2020
Derivatives
Risk management
Machine learning
Deep learning

The paper presents a novel computational framework, the Deep xVA Solver, for portfolio-wide counterparty credit risk management. It addresses the challenge of high-dimensional risk factors by reformulating xVA computations as a system of backward stochastic differential equations (BSDEs) and solving them using deep neural networks. The method is built on a rigorous financial model that incorporates default risk, funding costs, and collateral agreements, leading to a pre-default xVA BSDE under the reference filtration. The algorithm parametrizes the hedging strategy at each time step by neural networks and optimizes them via stochastic gradient descent, making it feasible for high-dimensional problems (tested up to 100 assets). Key contributions include the ability to compute both non-recursive xVAs (CVA, DVA) and recursive xVAs (FVA) through a recursive application of the solver, and the simultaneous generation of hedge ratios and dynamic risk measures. Numerical experiments demonstrate basis point accuracy, efficient collateral simulation, and robustness across various test cases. The framework is adaptable to different xVA specifications and offers a significant improvement over traditional nested Monte Carlo and PDE methods in high-dimensional settings.

Highlights

  • 1Develops a neural network-based BSDE solver for portfolio-wide xVA computations, including CVA, DVA, FVA, and ColVA.
  • 2Handles high-dimensional risk factors (tested up to 100 assets) where traditional PDE methods suffer from the curse of dimensionality.
  • 3Provides a recursive algorithm for recursive xVAs like FVA and produces hedge ratios and dynamic risk measures.
  • 4Demonstrates basis point accuracy in numerical tests, with applications to collateral simulation and sensitivity analysis.

Methods

  • M
    Deep BSDE Solver: Parametrizes the control (hedging) process at each time step by neural networks and minimizes a loss function via stochastic gradient descent.
  • M
    Reduction to pre-default xVA BSDE under the reference filtration using immersion hypothesis and intensity-based default modeling.
  • M
    Recursive application of the solver for recursive xVAs (e.g., FVA) by solving a sequence of BSDEs.
  • M
    Monte Carlo simulation for forward SDEs and neural network approximation for backward components.

Results

  • R
    The Deep xVA Solver achieves accurate xVA values (within a few basis points) for portfolios with up to 100 underlying assets.
  • R
    The method successfully computes CVA, DVA, FVA, and ColVA in a unified framework, with hedge ratios obtained as by-products.
  • R
    Numerical tests show convergence with increasing number of training steps and network size, and robustness to different model parameters.
  • R
    The approach enables efficient simulation of collateral accounts and dynamic risk measures like potential future exposure (PFE).
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