Jennifer Garner was thrilled to ring the bell at NYC’s famed Stock Exchange. “We probably slept an hour each,” the 53-year-old told Fortune in early February. No wonder: The mom of three, who was accompanied by son Samuel, 13, had just brought her food company, Once Upon a Farm, public with a valuation of $845 million.

By the next day of trading, the stock price had gone up 40 percent from its $18 listing price. But Jen won’t be going on any spending sprees. As she explained, the company — which offers healthy baby food — is hoping to expand to include food for older kids.

More important, Jen and her cofounder want to keep their company out of the hands of a giant food conglomerate. Says Jen,…