When the $2.5 billion Ticketmaster-Live Nation merger received the green light from the U.K. Competition Commission on Tuesday (Dec. 22), that left all eyes turned toward U.S. and Canadian regulators who are reviewing the proposed combined company.

The U.K. approval, along with prior ones from authorities in Norway and Turkey, have no direct impact on other regulatory investigations, though Tuesday's ruling could help pave the way for other approvals, wrote Tuna Amobi, Standard & Poor's media and entertainment equity research analyst, in a published note. But, "we would be surprised if the deal secures DOJ approval without some meaningful concessions in key areas, such as ticketing or artist management," Amobi wrote.

The larger concerns regulators have are over the proposed company's control of ticketing. "Ticketmaster has venues under its [owned and operated] control, through the Live Nation merger, and it is more than fair to say that realistically these venues will never be serviced by anyone outside of Ticketmaster if the deal goes through," wrote Thomas Weisel Partners media and entertainment research analyst Ben Mogil in a published research note on Dec. 21. One potential concession for DOJ approval? The inclusion of a secondary ticketing partner - possibly CTS Eventim or Comcast's New Era Tickets - at Live Nation owned and operated venues.

If the DOJ ultimately rejects the merger, expect a battle. "What we are fairly certain of is that both companies will fight any DOJ lawsuit aggressively as they have already spent $48mn in merger related fees on this deal and suspect that the duration of the review indicates that the government's case has some challenges and that a suit is political," wrote Mogil.

The ticketing behemoth and the world's largest concert promoter were "optimistic there will be a successful outcome" in the U.S. and Canada, according to a statement.