Optimal trading under proportional transaction costs

A universal law for optimally dealing with proportional transaction costs

In this paper, we consider how to `optimally' deal with proportional transaction costs when trading a single asset that follows an arbitrary diffusion process. Many of the superficial differences between the various strands of research are unimportant, and there is a universal law that we formally publish here. Although the literature on the subject is reasonably large, there is very little on applications in systematic trading algorithm design. The purpose of this paper is therefore to concentr