Hilton Hotels Corp. has sued by a shareholder claiming company directors didn’t get a high enough price when they agreed to sell to Blackstone Group LP for $20 billion earlier this week.

Investors should get more from the sale, which was announced July 3, than the $47.50 per share that Blackstone is offering, stockholder David B. Shaev said in a complaint filed in Delaware Chancery Court in Wilmington and made public on Friday.

Blackstone’s buyout of the nation’s second largest hotel chain would be the largest ever acquisition of a hotel company. Even so, “the consideration to be paid to Hilton Hotels stockholders under the proposed merger is grossly unfair, inadequate and substantially below the fair or inherent value of the company,” Shaey said in his complaint.

If the sale doesn’t go through, Beverly Hills-based Hilton must pay Blackstone $560 million. The complaint contends that the breakup fee is so high that it will discourage other bidders.