A new index listing companies making a social impact has been launched in a bid to raise the profile of socially responsible investing in the UK.

The Social Stock Exchange (SSE) is a listing company which admits businesses that are already publicly traded, and have the alleviation of social and environmental problems as a core principle.

It has launched with 11 companies ranging in market capitalisation from less than £1m to £269m. The largest companies by market cap are Primary Health Properties Plc, which lets property to the NHS, and water decontamination company HaloSource which has a market cap of £51.5m.

Companies seeking a listing on the Exchange will be vetted for their social impact credentials before admittance, and have their compliance to social aims regularly monitored.

Prominent philanthropy society The Rockefeller Foundation was an early backer of  the venture, which founder and chief executive officer Pradeep Jethi hopes will make it easier for charity investors, private offices and high-net-worth individuals to identify publicly-listed companies making a social impact.

“We are seeking to bring impact investing to the public equity capital markets. As a response to the financial crisis of the last five years the whole thesis of impact investing has gathered pace, and that means investing for mixed motives,” he said.

He highlighted research by J.P. Morgan which estimates there is £11.9bn invested in the socially responsible investing sector to show that many investors are motivated by factors other than just return on capital.

Although stocks cannot be traded on the SSE, Jethi is hoping increased investor awareness raised by the index will also help encourage more early stage funding into these ethical businesses.

“Now, hopefully, more angel investors will come into the space,” he said.

While Jethi admitted there is no clear definition of ‘social impact’, one company seeking a listing on the Exchange has been turned away for failing to demonstrate full commitment to a positive social impact.

Founder members of the Social Stock Exchange