Impax Asset Management Group, a British asset manager focused on sustainable investing, has closed the acquisition of US-based Pax World Management.

New Hampshire-based Pax provides actively and passively managed equity and fixed income strategies.

Since 2007, the two companies have been working together to manage the Pax Global Environmental Markets Fund.

Impax paid $52.5m initially for the deal, with contingent payments of up to $37.5m expected to be paid in 2021 based on the performance of Pax. The deal was first announced in September 2017.

Pax will now operate under the Impax Investment Management (US) name, though mutual funds managed by Pax will retain the Pax brand.

The existing management and investment teams of both the companies will be retained, with Pax president and CEO Joe Keefe continuing to head the firm.

Keefe will report to Impax CEO Ian Simm and will join the board of Impax’s London-based investment management arm known as Impax Asset Management.

Impax CEO Ian Simm said: “After a decade of partnership, I’m delighted that Impax and Pax are joining forces, creating an investment manager focused on the transition to a more sustainable economy. With assets under management of £11.3 billion ($15.3bn), and over 130 staff based in the UK, US and Hong Kong, the combined group is well positioned to offer a broad range of investment strategies to a global client base.”

London-based Impax offers actively managed global public equity and private equity strategies. The company also has offices in the New York metropolitan region, Portland in Oregon and Hong Kong.