Today Rosenfeld runs the newly formed Mondelez International, which started trading as a separate company Tuesday. It’s not as big as her old job, but she says she’s not bothered by the smaller scale. “As a woman, I don’t have to tell you that size is not everything,” she said.

A telling detail? The CEO said that men, in particular, were surprised that she would talk herself out of a bigger position. Regardless, with $36 billion in revenue, Mondelez is a global food powerhouse.

Read the full transcript of this interview

Rosenfeld spoke at Fortune’s Most Powerful Women’s Summit on Tuesday. On stage at the conference in California, she likened the new job to running the “world’s biggest startup.” Mondelez’s portfolio includes some of Kraft’s most iconic brands, including Oreo, Ritz, and Tang.

The snack food company is growing fast, Rosenfeld says, as people around the world change their eating habits. People are snacking more in “virtually every market.” Part of the reason is that more women are working, often eating on the go instead of taking the time at home to prepare meals.

The task of splitting the company was a formidable one, Rosenfeld said, involving separating 95,000 different trademarks. “Breaking up is hard to do,” she joked. “You need to do it for the right reasons.” It’s a great deal of work, she said, but “when it’s done right, it can create great value.”

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