Finite-horizon exponential-utility portfolio 2026-10-14
For exponential utility on unrestricted terminal portfolio wealth in the Black-Scholes model, the optimal dollar holding in the stock is the displayed deterministic amount. Set and let be the Brownian motion under the risk-neutral measure. The terminal optimizer is . Its marginal utility is proportional to the state-price density, and the concave supporting-tangent inequality proves global optimality under the state-price budget constraint. The expected utility at the optimum is . A nonnegative-wealth constraint changes this optimizer.