🤖 AI Summary
This paper addresses the optimal insurance contract design problem under the Lambda-Value-at-Risk (ΛVaR) framework, jointly accommodating heterogeneous risk sensitivity among policyholders and insurers’ robustness requirements. Methodologically, it pioneers the integration of ΛVaR into actuarial optimization—overcoming the rigid tail-risk assumptions inherent in traditional Value-at-Risk (VaR) and Conditional VaR (CVaR) by enabling continuous, preference-based tail-risk calibration. Leveraging convex analysis, distributionally robust optimization, and calculus of variations, the study constructs a structured solution framework incorporating monotonicity constraints and incentive compatibility. It derives explicit optimal reinsurance forms—e.g., stop-loss–stop-loss contracts—and establishes their existence and uniqueness. Numerical experiments demonstrate that the proposed ΛVaR-based contracts improve the joint expected utility of policyholders and insurers by 12%–19% relative to conventional VaR/CVaR benchmarks.