Online ticket seller Viagogo is buying eBay's StubHub platform.
Geneva-based Viagogo will buy StubHub for US$4.05bn (€3.67bn) in cash after the two firms entered into a definitive agreement.
StubHub is a major ticket seller in the United States.
Viagogo describes itself as "the world's largest secondary marketplace for tickets to live events."
However, it has been criticised in the past for price hikes on tickets.
The platform says that prices are set by sellers on its website and "may be below or above face value."
Combined, the companies will sell tickets across more than 70 countries.
Viagogo's founder and CEO is Eric Baker - who also co-founded StubHub while in business school.
He said: "It has long been my wish to unite the two companies. I am so proud of how StubHub has grown over the years and excited about the possibilities for our shared future.
"Buyers will have a wider choice of tickets, and sellers will have a wider network of buyers. Bringing these two companies together creates a win-win for fans - more choice and better pricing."
Sukhinder Singh Cassidy, president of StubHub, added: "Bringing StubHub and Viagogo together will allow us to drive further expansion and innovation, and create a more competitive offering for live event fans globally.
"This provides a great opportunity to expand our business, pursue new partnerships and execute our strategy.
"We expect a seamless transition for all our employees, partners and customers, and we are excited for what the future holds."
The sale is expected to close by the end of the first quarter of next year, subject to regulatory approval.
Stubhub was sold to eBay, the online retailer and marketplace, for US$310m (€281m) back in 2007.
Viagogo was founded in 2006 and serves customers in over 70 countries.