The London Stock Exchange expects its shareholders to vote on the proposed merger with Deutsche Boerse after the EU referendum.
The company said in a statement this morning that shareholder documents are expected to be published in June.
And its shareholders are then expected to be asked to vote at a meeting in July.
Deutsche Boerse told its shareholders last week that it hopes to complete the £21bn "merger of equals" in the last quarter of this year or in early 2017.
New York Stock Exchange owner the Intercontinental Exchange (ICE) earlier this month ruled out a bid for the London Stock Exchange, paving the way for the deal.
But analysts still have doubts that it will go through.
Exane BNP Paribas analysts believe there is more than half a chance the deal will be blocked. And Credit Suisse rates its chances of securing competition approval at 50-50.
However, the deal received a boost last week when chancellor George Osborne appeared to give it his backing.
Both the London Stock Exchange and Deutsche Boerse have dismissed the suggestion the EU referendum will affect their deal.
But German members of parliament have suggested a so-called Brexit would at least be a deal-changer.
Ulrich Caspar, a member of parliament for the ruling Christian Democrats in the state of Hesse, told City A.M. in April that the merged company's headquarters could "under no circumstances" be based in the London rather than Frankfurt if the UK leaves the EU.
Sources close to the deal have dismissed the prospect of a headquarters change, Brexit or not.
One told City A.M.: "The location of UK TopCo in London was a non-negotiable element of the merger and would not be revisited in the event of a Brexit vote."