City regulator the Financial Services Authority (FSA) is to implement the requirement in order to expose firms who take up "synthetic" positions, boosting transparency in the sector.
CFDs are a type of financial instrument used to "own" shares without the obligation of paying a type of tax known in Britain as stamp duty.
Commenting on the announcement to the Times newspaper, Sarah Bowles at Simmons & Simmons said: "This comes as a surprise."
An anonymous executive at a "major" investment house added: "It's a good thing. Give the FSA a tick."
As part of its drive for greater clarity in the financial sector, the FSA announced last month that firms who took up short-selling positions in companies which were undergoing rights issues at the time would also be required to make their moves public.