The company is owned by KKR & Co. and Affinity Equity Partners. It was first purchased by KKR from AB In-Bev for $1.8 billion in 2009, a year after Belgium's In-Bev purchased the American brewer for $52 billion.
Later, KKR sold half of Oriental Brewery, which makes Cass Beer, to Affinity Partners.
The Wall Street Journal reported the $5.8 billion sale is the largest ever exit from a company by a private equity firm in Asia.
The price for the deal was preset, the Journal said, having been established in 2009 when KKR bought the company.
At that point, it was agreed In-Bev would have the right to buy back the company at a price nearly 11 times the estimated earnings before tax, depreciation and amortization by July 2014, sources close to the deal told the Journal.
Cass is the best-selling beer brand in South Korea. The company also produces third-party brands, such as Blue Girl, the best-selling beer in Hong Kong, and Cass Red, which is the best-selling beer in Mongolia, the Journal said.
In the past four years, Oriental Brewery overtook Hite-Jinro Co. as the top-selling South Korean brewer. It also has a strong export business with $63.3 million in export sales in the first six months of 2013.