The Competition And Markets Authority's (CMA) investigation of Viagogo's takeover of StubHub has provisionally found competition concerns.

The watchdog, which referred the acquisition for an in-depth investigation in June, is concerned the $4.05 billion deal would result in a "substantial lessening of competition" (SLC) in the secondary ticketing marketplace and lead to increases in fees for customers, a lower quality of service and reduced innovation in the sector. The companies have a combined market share of more than 90%.

The CMA has set out potential options to address its concerns, which include requiring Viagogo to sell all or part of StubHub. It is now invited submissions from interested parties by 5pm on Thursday, November 12.

Stuart McIntosh, chair of the CMA inquiry group, said: "The evidence we’ve seen so far consistently points in the same direction – that Viagogo and StubHub have a market share of more than 90% combined and compete closely with each other. We are therefore concerned that their merger could lead to secondary ticketing customers facing higher fees and lower quality services. We’re now inviting comments on our provisional findings and possible remedies."

Adam Webb, campaign manager for anti-touting pressure group FanFair Alliance, said: "Though poorly-timed and focused predominantly on the US market, Viagogo's $4.05bn acquisition of StubHub raises acute competition concerns in the UK. We are pleased the CMA has recognised this.

"Ultimately, this merger would bestow a hugely controversial business monopoly status in this country, and risk unpicking some significant progress made over recent years to clean up the secondary ticketing market. We now look forward to submitting further views to the CMA about both their findings and potential remedies."