Shares in the London Stock Exchange leapt by almost 9 percent Tuesday after its New York rival announced that it was considering bidding for the company.
Atlanta-based exchange and clearing house operator Intercontinental Exchange Inc said it was pondering an offer for London Stock Exchange Group, a move that could derail Deutsche Boerse AG's potential tie-up with the British company.
ICE said it had not yet approached the board of LSEG and no decision has been made as to whether to pursue such an offer.
Shares in LSEG, which had a market value of $13 billion as of Monday's close, rose as much as 8.8 percent to a record high on Tuesday.
LSEG on Tuesday said it had not received a proposal from ICE and that its talks with Deutsche Boerse were continuing.
Bloomberg, which first reported ICE's interest, also said CME Group Inc is also working with advisers to potentially challenge a deal between LSEG and Deutsche Boerse, citing people familiar with the matter.
Deutsche Boerse could not immediately be reached for comment. A spokesman for CME declined to comment on market rumors or speculation.
LSEG and Deutsche Boerse last week confirmed they were in talks to create a European trading powerhouse and propel the companies to a similar scale as U.S. exchange ICE, which has taken a huge slice of the European derivatives market.
"It's going to force anybody that has been potentially looking at (LSEG) to step up or go away," Numis Securities analyst Jonathan Goslin said, adding Euronext NV, CME and Hong Kong Stock Exchange have been touted as potential bidders.
Atlanta-based ICE must make an offer for LSEG no later than March 29. Under British takeover rules, Deutsche Boerse must either make an offer or announce it will not do so by March 22, unless it obtains an extension from the UK mergers regulator.