DraftKings is making a $20 billion offer to acquire U.K. online sports betting company Entain, people familiar with the matter told CNBC’s David Faber on Tuesday.

The offer is largely in DraftKings stock, along with cash, according to the sources.

Entain shares jumped about 18% in London trading Tuesday. DraftKings shares closed 7.4% lower Tuesday after the news.

On Monday, before news of the deal, the enterprise value of Entain was about £13.2 billion, or $18 billion.

In a filing with the London Stock Exchange, Entain’s board confirmed that it received a proposal from DraftKings, which would include a combination of stock and cash. The filing did not contain any information on the price of the offer.

“A further announcement will be made as and when appropriate,” Entain noted in the filing. “Shareholders are urged to take no action at this time.”

The U.K. gaming company rejected an all-stock offer from MGM Resorts earlier this year worth $11 billion at the time. Entain said the deal significantly undervalued the company.

MGM and Entain have an online sports betting partnership in the U.S. called BetMGM.

While MGM is not involved with DraftKings’ bid for Entain, MGM’s consent is required for any deal involving the U.S. assets of Entain, the company said.

“Any transaction whereby Entain or its affiliates would own a competing business in the U.S. would require MGM’s consent,” the company said in a statement. “MGM will engage with Entain and DraftKings, as appropriate, to find a solution to the exclusivity arrangements which meets all parties’ objectives.”

DraftKings has not returned CNBC’s request for comment.

Entain’s brands include U.K. poker and gambling companies Coral, Ladbrokes and PartyPoker.

DraftKings went public via a reverse merger with a special purpose acquisition company in 2020. The online gaming giant operates fantasy sports contests and sports betting.