The owner of the New York Stock Exchange, Intercontinental Exchange (ICE), has confirmed it is considering making a takeover offer for the London Stock Exchange (LSE).
It comes a week after the LSE confirmed it was in merger talks with Germany’s Deutsche Boerse.
In a statement, ICE said no approach had been made to the LSE board, and there could be no certainty that an offer would be made.
LSE shares jumped 7% on the news.
Under UK merger rules, ICE must now make or announce an offer for the LSE no later than 29 March.
Last week, the LSE confirmed it was in “detailed discussions” with Deutsche Boerse about a “merger of equals”.
Both companies said all their key businesses would continue to operate under their current brand names.
It is the third time the LSE and Deutsche Boerse have tried to strike a deal, with the first attempt in 2000 then another in 2004-05.
Under the terms of the latest plan, the LSE would own 45.6% of the merged group and Deutsche Boerse would hold the remaining 54.4%.
The combined business would have a single board, made up of an equal number of directors from the two companies.