Maple Group, the collection of Canadian banks and pension funds battling the London Stock Exchange for control of TMX, has taken its bid hostile.
Last week the TMX Group board rejected the C$3.6 billion Maple offer, reaffirming its commitment to a tie-up with the LSE.
The Canadian operator has now obtained an interim order of the Ontario Superior Court of Justice, enabling it to hold a shareholder vote on the LSE proposal on the 30 June.
However, the Maple consortium has refused to back down, with spokesman Luc Bertrand, from National Bank of Canada, saying: "They have given us no choice but to make our offer available directly to TMX Group shareholders."
Maple has significant support in Canada, with nationalist sentiment against the LSE agreement rife but there are concerns a deal could face antitrust hurdles.
If the consortium manages to hijack the bid, there is growing speculation that the LSE will be vulnerable to a takeover itself, with Nasdaq OMX and the Singapore Exchange both looking for deals having had other targets fall through.