Impax Asset Management has seen its assets rise 13 per cent in Q2 hitting £5.7bn at the end of the quarter.
Assets sat at £5.1bn at the start of the quarter.
Its listed equity funds surpassed £5bn over the period, rising from £4.6bn to £5.3bn, bolstered by £428m inflows.
A further £375m sits in private equity and £22m in property funds.
Chief executive Ian Simm says: “We are seeing sustained interest from investors in many countries who are looking to access superior expected returns.
“With the Company’s assets under management exceeding £5 billion, we continue to scale existing products across both listed equities and real assets, while also considering the development of our product range in response to client interest.”
Impax focuses on environmental markets and resource efficiency sectors and is listed on the Aim market.