The deal still requires approval from gambling regulators in more than a dozen states and several tribal nations where Harrah's operates. The European Union signed off on the deal on Wednesday after finding no reasons for concern and receiving no third-party complaints. The buyers won't likely go in front of Nevada gaming officials until this fall. Subject to those approvals, Harrah's says it expects the transaction to be completed by the end of the year.

Harrah's is the world's largest casino company by revenue. It operates 39 casinos across the United States, including Caesars Palace, Bally's, Flamingo and Paris on the Las Vegas Strip. International, it owns stakes in casinos in Canada and Uruguay and owns U.K.-based London Clubs International PLC, which operates 10 casinos in UK, Egypt, and South Africa.

In addition to paying $17.1 billion for the company's outstanding shares, the private equity firms will assume $10.7 billion in debt. The result of the deal will be a near doubling of Harrah's debt load, which will require it to focus on paying down that debt rather than reinvesting in growth, according to related documents filed with the Securities and Exchange Commission.