(Bloomberg) -- U.S. casino operator MGM Resorts International said it decided not to make a firm offer for Entain Plc after the U.K. gambling company dismissed its $11 billion takeover attempt. Entain shares slumped as much as 20% in London.A merger would have given MGM full control of BetMGM, the two companies’ U.S. joint venture and a beachhead in a market seeing rapid growth. Under the proposed terms, Entain investors would have exchanged stock for 0.6 of a share of MGM and would have held about 42% of the combined business.In a statement Tuesday, MGM said that “after careful consideration and having reflected on the limited recent engagement between the respective companies regarding MGM’s rejected all-stock proposal,” it doesn’t plan to submit a new offer.The approach was the latest in a wave of trans-Atlantic gambling M&A activity since the U.S. Supreme Court legalized sports betting in May 2018, setting off a race for market share.European companies have expertise and technology while U.S. ones offer scale and market access. MGM’s Las Vegas rival Caesars Entertainment Inc. agreed to buy British bookmaker William Hill Plc for 2.9 billion pounds ($4 billion) in late 2020, and Ireland’s Flutter Entertainment Plc closed the acquisition of Canada’s the Stars Group earlier that year.MGM “will maintain a disciplined framework while evaluating a range of compelling strategic opportunities,” the Las Vegas company said in the statement.MGM shares rose as much as 4.9% in New York trading Tuesday. Entain, previously called GVC, was down 14% at 1,220.5 pence in London.Entain is confident its existing growth strategy will deliver stakeholder value, it said in a separate statement. MGM’s decision to walk away caps a difficult few weeks for Entain, with the company facing opposition to its own plan to acquire a smaller company called Enlabs and the unexpected departure of Entain’s chief executive officer. Shay Segev is leaving after less than six months in the role. “It’s been a rocky month,” said Goodbody analyst Gavin Kelleher. “But all told, everything that’s happened since Dec. 31, I think there’s more positives with Entain than negatives.” Kelleher said Entain on its own is able to gain a double-digit percentage share of the U.S. market, and its board was right to demand a higher offer from MGM. There was even potential for another deal between the two companies down the road, he added. (Updates with context, analyst comment at end)For more articles like this, please visit us at bloomberg.comSubscribe now to stay ahead with the most trusted business news source.©2021 Bloomberg L.P.