Impax Asset Management, the Aim-listed investment house, has reported a 13 per cent increase in assets under management for the three months to 31 December.
The company managed £8.2bn at the end of December, a figure that does not include the assets managed by Pax World Management, a business which Impax announced it would be buying in mid-December.
The transaction is still in the process of being completed.
The bulk of Impax's assets are held in listed equity funds, while they also managed £454m in private equity mandates and £22m in property fund assets.
Ian Simm, chief executive of Impax AM, said: "I am pleased to report on another outstanding quarter.
"Investor interest in the transition to a more sustainable economy continues to gather momentum and it is most encouraging to see further strong inflows across our fund range from clients in Europe and North America.
"Our pipeline remains promising for both our listed and private equity strategies."