The brands that are moving are Kellogg's kid's range (Corn Frosties, Choco Frosties, Chokowa, Choco Krispies, Variety), which join the adult brands already handled at JWT (Corn Flakes, Genmai Flakes, All-Bran, and Country Morning).
The switch came after a year-long review in which Kellogg's assessed both agencies. According to a source close to the review, "It was a performance review which measured the quality of agency services/products such as strategic planning and creative, consumer response, sales response and overall agency capabilities."
MindShare continues to handle media plannning for the account, with Asatsu-DK as media buying partner.