Entain Plc said that an increased offer from MGM Resorts International of about 8.1 billion pounds (US$11.1 billion) in shares undervalues the company.

Under the terms of the proposed deal, Entain investors would get 0.6 share of MGM for every share they hold and would own about 42 per cent of the combined company, Entain said in a statement on Monday. MGM may also offer a “limited partial cash alternative” to shareholders. At 1,383 pence per share, the bid is a 22 per cent premium to Entain’s closing share price on Thursday.

MGM, the largest casino operator on the Las Vegas Strip, formed a joint venture in 2018 with Entain, formerly known as GVC Holdings Plc, to capitalize on the growth of online betting in the U.S. The partnership got off to a slow start as the venture had some disagreements over strategy.

A merger would consolidate control of the company’s online betting operations at a time when the industry is seeing dramatic growth. The U.S. sports betting market alone is expected to quintuple in size to US$8.4 billion by 2024, according to the consulting firm Vixio Gambling Compliance.

Entain has asked MGM for more details on the strategic rationale on the combination and has asked shareholders to take no action.

Entain shares gained 28 per cent last year, giving it a market value of 6.6 billion pounds. MGM shares fell 5.3 per cent in 2020.