Duesenberry introduced the notion of a ratchet investor who does not tolerate any decline in her consumption rate. We connect the demand behavior of such an agent to the behavior of standard time-additive agents. A ratchet investor demands the running maximum of the optimal plan a conventional...

We consider optimal consumption and portfolio choice in the presence of Knightian uncertainty in continuous-time. We embed the problem into the new framework of stochastic calculus for such settings, dealing in particular with the issue of non-equivalent multiple priors. We solve the problem...

The utility maximization problem of "ratchet investors" who do not tolerate any decline in their consumption rate is solved explicitly for all felicity functions in a Markovian framework which includes Brownian motion and Poisson processes as special cases. The optimal consumption plan turns out...

We study the intertemporal utility maximization problem for Hindy-Huang-Kreps utilities. Necessary and sufficient conditions for optimality are given. An explicit solution is provided for a large class of utility functions. In particular, the case of separable power utilities with a finite time...