Britain's planned exit from the European Union has raised questions about plans by Germany's Deutsche Boerse and the London Stock Exchange (LSE) to base themselves in London once they have completed their merger.
Despite assurances from both companies in the wake of the announcement that Brits voted in favour of Brexit that were "fully committed" to the merger, criticism of London as a headquarters have resurfaced.
Frankfurt-based Deutsche Boerse and the LSE said in March that they had agreed to the terms of an "industry-defining" merger that would create a European trading powerhouse with its legal headquarters in London.
Regulators in the German state of Hesse, where Deutsche Boerse is based, have expressed doubts as to whether London is viable as a legal headquarters for the merged entity. They have the power to block the merger.
Deutsche Boerse's works council said Friday that Britain's decision to leave the bloc made Frankfurt the only viable headquarters.
"We are not calling for the merger to end, but that the main headquarters be moved to Frankfurt," said Jutta Stuhlfauth, the head of the workers council.
The companies said on Friday that they would continue to seek regulatory clearance in the European Union, the United States and Russia.
"The decision of the UK to leave the EU makes it ever more important to maintain and foster ties between the UK and Europe," said Joachim Faber, who chairs Deutsche Boerse's supervisory board.