American call option American options Bayesian learning Hamilton-Jacobi-Bellman equation Markov additive processes Markov regime switching market Markovian jump securities Markowitz problem asymptotic arbitrage binomial tree complete market debt crisis decision analysis derivatives pricing energy imbalance market excess-of-loss reinsurance free boundary problem general diffusion geometric Brownian motion government debt management government debt ratio insurance least square method martingale multiple optimal stopping optimal government debt ceiling optimal portfolio optimal reinsurance optimal stopping portfolio selection