Parnassus Investments chief investment officer Todd Ahlsten has a distinction few others can claim — he is running the largest ESG fund in the US.

The Parnassus Core Equity Fund currently weighs in at $26bn and Ahlsten has run the strategy since 2001 when he was 29 years old. Including other versions of the strategy, such as the ABN AMRO Parnassus US ESG Equities Fund available in Europe, that figure is closer to $33.5bn.