Sarah MacMillan is the great-great-granddaughter of W.W. Cargill, who launched the Cargill empire in 1885 by opening a small grain store in Iowa. The company remains one of the largest grain commodities traders in the world and the largest privately owned business in the United States. The company reportedly saw revenue grow by 2 percent in 2017 to $109.7 billion. MacMillan inherited a 3 percent stake in the company in 2006. She has an estimated net worth of $1.6 billion and is No. 43 on the Los Angeles Business Journal’s list of Wealthiest Angelenos. She lives in Malibu and keeps a low profile.