Citi is set to choose Frankfurt as its main base of operations in the European Union as part of preparations ahead of the UK leaving the bloc in March 2019.
Frankfurt will be a hub for its sales and trading operations and will see several hundred jobs moved out of London after Brexit, according to reports.
US-headquartered Citi is one of many banks considering moving some operations out of the UK in the wake of the referendum vote to leave the EU in 2016.
Deutsche Bank, BNP Paribas, Barclays and Bank of America are all thought to be exploring options to shift thousands of jobs onto the European continent or to Ireland in response.
The move is likely to increase pressure within the UK government to temper its Brexit strategy, which has come under strain since the Conservative Party lost its majority in an early general election in June. Recent weeks have seen intense infighting as factions within the government seek to direct the course of Brexit, with those backing a so-called soft Brexit gaining in confidence since the election result.
In Germany, a local industry association said Frankfurt could see the creation of up to 5,000 new jobs as a result of the UK’s departure from the EU.