If you invest in a fund that claims to be sustainable or green, how can you be certain that it is everything that it claims to be? There is no easy answer but the European Securities and Markets Authority (Esma) wants funds to be upfront about how they name themselves. Last week, the EU regulator published its long-awaited guidelines on how to name funds that are making investments in sustainability and ESG businesses, after a lengthy consultation process that saw industry weighing in heavily. Chief among the new guidelines is just how much investing a fund does in green endeavours.…