Giovanni Ferrero has expanded his family's company beyond brands like Nutella and built a global powerhouse—especially through big acquisitions in the U.S.

Ferrero International has agreed to acquire WK Kellogg Co. for an enterprise value of $3.1 billion, pushing the Italian family-owned candy business further into the lucrative U.S. market.

The deal combines the maker of Nutella with the company behind Froot Loops cereals, diversifying its chocolate-heavy portfolio at a time of high cocoa prices.