Brexit has pushed the UK's Social Stock Exchange to consider establishing itself in Brussels or Amsterdam, the chief executive has said.
The Social Stock Exchange (SSX) was launched by the Conservative government in June 2013 to spearhead social and impact investment in the UK and make London a world leader in bringing impact businesses to the public markets.
However, Tomas Carruthers, who became chief executive of the SSX in December 2013, said the vote to leave the European Union would have a serious effect on the SSX and the companies it lists.
He said: "The United Nations is global; impact investing is global and we do not want to end up in a protectionist environment.
"The SSX does not want to be British. It wants to be European - global even - and bring the best of all impact companies from around the world to list.
"To be European we will have to open in Brussels or Amsterdam."
He said regardless of what will happen with the eventual negotiations to leave the EU, operating from the eurozone would be "cost effective and business critical for the SSX".
Already the SSX has European companies seeking to list, such as Netherlands-based company Solarus Power or fellow Dutch co-operative Oikocredit Ecumenical Development Cooperative Society.
According to the latest data, 10 out of the 44 current members have their headquarters registered outside of the UK.
Mr Carruthers added: "We are optimistic we can see the creation of businesses that genuinely have a social purpose, and give them access to the public markets in a way that provides a liquid model."