CME Group Inc. has offered to buy U.K. financial-technology company NEX Group PLC, a deal that would put the Chicago futures-exchange giant in a commanding position in the vast market for U.S. government debt. NEX said in a statement on Wednesday that it had received a nonbinding takeover offer of GBP10 a share, the equivalent of $14.08. That would value the London-based company at about $5.4 billion. NEX said discussions were at an "advanced stage." There is no certainty as to whether an offer will be made, or what the terms of an offer would be, NEX said. Representatives of CME and NEX declined to comment. The two companies confirmed earlier this month that CME had made a preliminary takeover approach to NEX. The news set off speculation that other bidders could emerge for NEX, such as Intercontinental Exchange Inc., owner of the New York Stock Exchange, or London Stock Exchange Group PLC. It also triggered a surge in NEX's stock price, which is up 45% since reports of the talks emerged on March 15.via