The UK's Competition & Markets Authority (CMA) has launched a Phase 1 inquiry into Viagogo's $4.05 billion (£3.2bn) acquisition of rival secondary ticketing site StubHub.
The watchdog opened an investigation into the deal in December 2019 to consider whether it would be "expected to result in a substantial lessening of competition within any market or markets in the United Kingdom".
The CMA, which has served a commencement notice, will announce its decision on whether to refer the merger for a Phase 2 investigation by June 11.
A Viagogo spokesperson said: "We welcome the formal start of the Phase 1 review by the CMA. We will continue to work closely with them and demonstrate the benefits of the merger for consumers."
Earlier this year, the CMA served an enforcement notice to Viagogo and StubHub as it investigates the proposed merger between the two resale sites, saying it had "reasonable grounds for suspecting" the businesses were already merging prior to the conclusion of its inquiry.
FanFair Alliance, which campaigns against industrial-scale online ticket touting, previously raised competition concerns over the deal and urged the CMA to investigate, alleging it would give Viagogo a monopoly over the "for-profit" secondary ticketing market in the UK.
“We welcome the formal start of the phase 1 review by the CMA," said a Viagogo spokesperson. "We will continue to work closely with them and demonstrate the benefits of the merger for consumers."