Paper: arXiv 2311.13802

Authors: Eva Lütkebohmert, Julian Sester, Hongyi Shen

Abstract

Sovereign loan portfolios of Multilateral Development Banks (MDBs) typically consist of only a small number of borrowers and hence are heavily exposed to single name concentration risk. Based on realistic MDB portfolios constructed from publicly available data, this paper quantifies the magnitude of the exposure to name concentration risk using exact Monte Carlo simulations. In comparing the exact adjustment for name concentration risk to its analytic approximation as currently applied by the major rating agency Standard & Poor’s, we further investigate whether current capital adequacy frameworks for MDBs are overly conservative. Finally, we discuss the choice of appropriate model parameters and their impact on measures of name concentration risk.

Complexity vs Empirical Score

  • Math Complexity: 5.5/10
  • Empirical Rigor: 6.5/10
  • Quadrant: Holy Grail — high math complexity, high empirical rigor

Why this score: The paper presents a practical and relevant quantitative assessment of name concentration risk tailored to MDB portfolios. It effectively compares exact Monte Carlo simulations against rating agency analytical approximations, providing solid empirical insight despite relying partly on reconstructed public data.

Research Flowchart

  flowchart TD
    A[Evaluate MDB Name Concentration Risk & S&P Framework Conservatism] --> B[Input: Public Data for Realistic MDB Sovereign Loan Portfolios]
    B --> C[Monte Carlo Simulations for Exact Risk Adjustments]
    B --> D[Analytic Approximation via S&P Capital Adequacy Model]
    C --> E[Sensitivity Analysis of Key Model Parameters]
    D --> E
    E --> F[Findings: Quantified Exposure & Assessment of Framework Conservatism]

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