In recent years there has been a significant increase of interest in
continuous-time Principal-Agent models, or contract theory, and their
applications. Continuous-time models provide a powerful and elegant
framework for solving stochastic optimization problems of finding the
optimal contracts between two parties, under various assumptions on the
information they have access to, and the effect they have on the
underlying "profit/loss" values. This monograph surveys recent results
of the theory in a systematic way, using the approach of the so-called
Stochastic Maximum Principle, in models driven by Brownian Motion.
Optimal contracts are characterized via a system of Forward-Backward
Stochastic Differential Equations. In a number of interesting special
cases these can be solved explicitly, enabling derivation of many
qualitative economic conclusions.