Forty top eurosceptics from the worlds of business and politics have come out against the London Stock Exchange's proposed £21bn mega-merger with Deutsche Boerse, calling for the deal to be blocked until after Brexit negotiations.
They say the deal, which is currently being evaluated by the European Commission, is a risk the government should "not be taking now".
The letter, signed by senior figures including former chancellor Lord Lawson, CMC Markets chief executive Peter Cruddas and serial entrepreneur Luke Johnson, says it is "in the international interest" for any approval to be delayed until after Brexit talks close in April 2019.
"The exchange is a key national asset, and in the wake of this merger the London Stock Exchange would find itself majority owned by Deutsche Boerse.
"The commercial logic would be for the new owners to build on London’s strength and reputation – but the political risk is the UK is forced to cede control and regulation to Frankfurt,” the group warn.
“The merger could also enable the Eurozone to realise its ambition to repatriate euro clearing. That would be very bad for London.”
The group was co-ordinated by former LIFFE boss Daniel Hodson, who was involved in Vote Leave and is a non-exec at Nasdaq. The letter is published in The Times today.
Other signatories include Lord Flight, Labour donor and businessman John Mills, City investor Edmund Truell, former business lobby boss John Longworth, economist Ruth Lea, and former broker Brian Winterflood.
Responding to the letter, a source close to the LSE told City A.M.: "This merger will create a leading financial market infrastructure group, domiciled in the UK, benefiting customers, the City and the wider economy."