The LSE became a potential target for Nasdaq chief Bob Greifeld after it failed to tie-up an agreed merger with Toronto bourse operator TMX Group.
Greifeld is understood to have asked his senior executives to look at putting together an approach.
A source told City A.M. that he is under pressure to seek merger opportunities because Nasdaq risks being dwarfed by bigger rival NYSE following its tie-up with Deutsche Boerse.
The New York-based exchange is said to have a price of about £12.75 per share in mind for the LSE. Shares in the London bourse closed at £10.33 per unit on Friday.
Meanwhile, the stock exchange has played down suggestions that two of its senior directors are under pressure from Artemis, a key shareholder, to quit following the collapsed merger.
Investors are said to have called for Robert Webb and Dame Janet Cohen, who have been on the board for ten years, to stand down.
An LSE spokesperson said: “In reference to Artemis, we have been informed that they have been and remain in support of the LSE board.”