General Mills today announced its plans to purchase the branded cereal and snack mix businesses of Ralcorp Holdings, including the Chex and Cookie Crisp brands, for $570 million. The deal includes a Cincinnati manufacturing facility and trademark and technology rights for these branded products in the Americas. The Chex line has about a 3% share of the ready-to-eat cereal market. General Mills' Big G cereal line has an estimated 24% of the market, ranking No. 2 behind Kellogg Co. Ralcorp's other businesses, including private-label cereals, baby food and private label cracker and cookies, will be spun off as a new, independent public company.