HSBC (LON:HSBA) has become the first major bank to give detail on their plans post-Brexit, saying it will relocate 20 percent of its London banking operations to Paris.

In a major blow to London, HSBC has confirmed plans to relocate jobs to elsewhere in Europe – something they warned before Britain’s referendum in June.

“We’re not moving this year and maybe not even next year,” said HSBC chief executive Stuart Gulliver. “We will move in about two years time when Brexit becomes effective,”

It is estimated that 1,000 jobs who are involved in trading will move, trading that contributes $384 million in the UK in 2015 according to the company.

“Activities specifically covered by EU legislation will move, and looking at our own numbers, that’s about 20 percent of revenue,” Gulliver said at the World Economic Forum in Davos, Switzerland.

The best hope for the City of London, which expects many other financial firms to announce similar news, is for banks to retain their EU ‘passporting rights’ which lets them sell their services across the bloc. This is possible if the government agree to a transitional arrangement where banks can continue to operate out of Britain and across the EU after Brexit, in the hope that a favourable access deal is achieved in the interim.

Mark Boleat, policy chairman at the City of London Corporation, said in a statement after Theresa May’s speech on Tuesday: “We would like to see a transitional agreement announced as soon as possible,”

Gulliver has said that despite the relocation of trading, London will remain a core financial centre.

“Irrespective of Brexit, London will remain a global financial centre, and the revenue impact of Brexit on financial services will be made good in two to three years’ time,” he said.

HSBC shares were up 1.89 percent by 1269 GMT.