Los Angeles ? Hilton Hotels Corp. said Tuesday it has agreed to be acquired by The Blackstone Group LP for $18.5 billion in cash.

The private equity group agreed to buy all outstanding Hilton shares for $47.50 each, a 32 percent premium over Tuesday’s closing stock price.

The companies valued the deal at $26 billion including debt.

Hilton’s board approved the terms Tuesday. The company said the deal would close in the fourth quarter pending shareholder approval.

“Our board of directors concluded that this transaction provides compelling value for our shareholders with a significant premium,” Stephen F. Bollenbach, Hilton’s co-chairman and chief executive, said in a statement.

The acquisition would take Beverly Hills-based Hilton Hotels private and boost Blackstone’s portfolio of lodging properties. Blackstone owns more than 100,000 hotel rooms in the United States and Europe, including La Quinta Inns and Suites as well as LXR Luxury Resorts and Hotels.

Hilton Hotels owns or operates 2,800 hotels and 480,000 rooms in 76 countries and territories and includes such brands as Doubletree, Embassy Suites and Hampton Inn.