Ralcorp Holdings released details Tuesday of how it plans to spin off its Post business unit as a free-standing company.

Holders of Ralcorp common stock at the close of business on Jan. 30 will receive at least 80 percent of the outstanding shares of Post common stock. Each shareholder will receive one share of Post common stock for every two shares of Ralcorp common stock.

“The separation will enable both companies to focus on their respective business strategies, while allowing investors to select discrete themes in terms of branded and private-brand foods,” said William Stiritz, chairman of Ralcorp’s board of directors.

Ralcorp. acquired Post in August 2008, in a deal valued at $2.6 billion. It was the third largest manufacturer of branded ready-to-eat cereal in the United States, with such well-known brands as Grape-Nuts, Honey Bunches of Oats and Post Raisin Brand.

The spinoff plan was announced last year as a way to unlock value for shareholders, amid a unsolicited acquisition offer for Ralcorp from Conagra that was rebuffed.

Plans call for the distribution to take place at 11:59 p.m. Eastern Time on Feb. 3, although the date could be extended if all necessary conditions have not been satisfied.

Some 34.5 million shares of Post common stock are expected to be outstanding immediately following the separation.

The separation is expected to qualify as a tax-free distribution to Ralcorp shareholders for U.S. federal tax purposes. Cash received in lieu of fractional shares will, however, be taxable.

Ralcorp produces private-label cereals at a mill in Cedar Rapids.