Australia's Macquarie Bank Ltd and financial services firm Computershare Ltd may make a take-over bid for the London Stock Exchange, a source familiar with the situation said on Thursday.
Macquarie would lead such an offer, which is unlikely to come before the middle of October if it is made, and Computershare would be a passive equity investor, the source said.
The Daily Telegraph newspaper reported earlier that an offer would be launched within days. Macquarie, Australia's biggest investment bank, and Computershare, the world's top share-registry firm, both declined to comment on the situation on Thursday.
After similar press reports in August, the LSE said it had not received a formal bid approach from Macquarie and that it remained confident about its prospects as an independent company.
The LSE declined to comment on the latest speculation.
"We have nothing more to add than what we said in August," a spokesman for Macquarie Bank said. Macquarie, which has 350 staff in London, said in August Europe's largest stock market operator was one of a number of potential acquisitions it was considering.
Some elements of the possible bid are still to be finalised, the source said, meanwhile, adding the timetable remained unclear and while no bid was currently anticipated before October 16, this could change.
Shares in the LSE were 1.6 percent higher at 579 pence on Thursday - valuing the exchange at about 1.5 billion pounds ($2.65 billion) - although still some way below the 700 pence a share touted by recent press reports as the level the LSE board would hold out for.
"Euronext can derive something like 160 million euros of synergies and with those synergies it can justify a maximum 660p share price," said Mamoun Tazi, analyst at Man Securities.
Approaches to the LSE from both pan-European exchange Euronext and Frankfurt-based Deutsche Boerse are still being considered by Britain's competition commission, which is expected to issue a final decision by November.
Although Deutsch Boerse has said it may re-enter the race to buy the LSE if Euronext makes an offer, the French-based exchange is still tipped as the most likely winner by sources familiar with the deal.
"The political skills of Euronext in satisfying different constituencies is very high," said one industry observer who declined to be named.
Macquarie Bank said in August it may team up with other investors to make a cash bid for LSE.
Traditionally, the company is known for buying infrastructure companies such as airports and utilities that occupy a monopoly position in their industry.