A few years ago, I began working with a progressively-minded couple who specifically requested me to construct a portfolio based on ESG (Environmental, Social and Governance) factors. I was happy to oblige and so I built them a portfolio using Exchange Traded Funds focused on these factors, whilst largely mimicking my traditional allocation models. Interestingly enough, I noticed over the years that the performance of their portfolio was among some of the best of all my clients. This began to pique my curiosity as to whether sustainable investing was also sustainably profitable. [In this post, for simplicity, I will treat ESG, Sustainable, Socially Responsible and Impact investing as synonyms.