Viagogo has been ordered to sell all of Stubhub’s businesses outside of North America including Britain by the UK’s competition authority.
Viagogo bought its ticketing rival in February for US$4.2bn, but had already been warned that the CMA saw them that as close rivals in an already very concentrated market with no significant additional competitors.
In the UK, Viagogo and StubHub are the two main providers of secondary ticketing platforms with a combined market share of more than 90%.
Concluding its review, the CMA said that the merger would lead to a substantial reduction in competition in the secondary ticketing market in the UK.
This could lead to customers who use secondary ticketing platforms facing higher fees or poorer service in future.
As well as the UK, the two companies operate in North America, several countries in Europe, and South America and Asia.
Any buyer will need to get CMA approval while details such as the use of the StubHub name still need to be decided.
Viagogo had already incurred the wrath of the CMA due to complaints about seating information, a lack of consumer protection and allowing ticket touts to resell tickets on the site at eye-watering mark-ups far beyond the price of the original ticket.
The UK-based group was threatened with court action by the CMA over how it presented key ticketing information to customers, such as advertising tickets without seat numbers or not warning buyers that they may be turned away from an event for buying resold tickets.
"Creating a fully independent StubHub international business will maintain competition in the UK and help ensure that the users of these ticketing platforms don’t face higher prices or poorer quality of service," said Stuart McIntosh, chair of the CMA inquiry group.