Steve Wynn sold 4.1 million shares of Wynn Resorts at $180 per share, the filing showed, which now makes him the third-biggest shareholder in the company, behind his former wife Elaine Wynn and The Vanguard Group Inc, according to Thomson Reuters data.
Wynn Resorts' shares dipped 0.8 percent to $177.50 in trading ahead of the opening bell.
The casino mogul's share sale comes a week after Wynn Resorts said Steve and Elaine Wynn, who has a 9.26 percent stake, had scrapped a shareholder agreement that prevented them from selling their stakes.
Steve Wynn resigned as CEO of the Las Vegas-based company last month, following claims he subjected women who worked for him to unwanted advances. He has denied the accusations.
Analysts have said Wynn Resorts may become a takeover target following the departure of Steve Wynn, who was a strategic visionary and the chief diplomat for the company.
Elaine Wynn said in a regulatory filing earlier this week that she may hold talks with Wynn Resorts shareholders and management regarding the company's strategy, capital structure and allocation, and board composition, among others.