Apollo Global Management Inc. is buying United Living, a UK provider of maintenance and construction services focused on the affordable housing sector, as the private-equity firm steps up investments dedicated to social responsibility.

The deal is the first in the UK for Apollo’s $1 billion impact fund, which has made four other investments globally. Financial terms weren’t disclosed in a statement Tuesday but people with knowledge of the transaction said it valued the Kent-based company at more than £300 million ($370 million).

Apollo wants to invest in more mid-market companies including those engaged in education, health, safety and climate sustainability, Joanna Reiss, a partner and co-head of impact, said in an interview. The fund seeks opportunities in developed markets where it has experience and investing expertise.

“There are already a number of firms that are focused on emerging markets and we are rooting for all of them,” Reiss said. “For us, there is a sense of humility in this so we want to focus on markets that we are best positioned to succeed financially in and also have the right impact. Even in wealthier nations, there are people who are struggling to heat their homes or eat a full meal.”

Apollo joins Brookfield Asset Management Ltd., KKR & Co., TPG Inc. and Bain Capital in seeking to raise money and deploy capital into socially responsible investing in response to demand from institutions. Investor allocations to impact investing, which targets specific environmental, social or governance outcomes instead of just screening for ESG risks, now stands at more than $1 trillion, according to the Global Impact Investing Network.

Unlike some of its Wall Street peers, who are mainly focused on early-stage and venture investing, Apollo is keen to invest in later-stage, mature companies like United Living where “capital is vanishing quickly,” Reiss said. The fund is currently more than 50% deployed and Apollo continues to focus on finding new investments and managing it’s existing portfolio, she said.

United Living operates infrastructure, property services and new homes units with a focus on increasing residential access to underserved populations. The company generated revenue exceeding £530 million in the year ended March 31, and employs more than 1,000 people.

For Apollo, the UK deal follows the acquisition last year of Miller Homes, a homebuilder in England and Scotland, for more than £1 billion.