The offering is valued at as much as $643.4 million. The Las Vegas company said it would use the funds for general purposes.
Deutsche Bank, Goldman Sachs and Bank of America are lead bookrunning managers for the offering.
The underwriters have an option to buy 825,000 more shares if demand for the offering requires.
The company is raising capital amid a tumultuous time for the gambling industry. Many casinos closed because of the coronavirus pandemic.
Operating revenue at Wynn for the fourth quarter were $686 million, a nearly 60% decline year over year.
For the year, operating revenue decreased 68% to $2.1 billion from $6.61 billion for all of 2019.
The company's Macau operations saw the least disruption last year, with the casino closing for just a 15-day period in February before resuming operations on a reduced basis.
While casino operations have been fully restored, the industry is still dealing with social distancing measures that are limiting the number of patrons allowed to congregate in the casinos.
Add to that the loss of revenue from live shows and other attractions and the industry has been hit hard in recent quarters.
Wynn's stock has rallied more than 46% over the past three quarters as investors, encouraged by the distribution of several vaccines, bought into the upgraded outlook for the coronavirus pandemic.
Wynn shares were falling 2.3% to $114.31. The stock closed Friday's session up more than 7.6%.