Key TakeawaysShares of the companies that dominate the shelves of America's supermarkets rose on Wednesday after Mars said it would buy snack maker Kellanova for $36 billion.Kellanova was spun out of cereal maker Kellogg late last year amid a slew of corporate separations by some of America's most storied companies.The Mars acquisition comes amid heightened regulatory scrutiny of grocery industry consolidation and a bout of inflation. Shares of the companies that dominate the center aisles of America’s gro ...