Gross was born in Middletown, Ohio, the son of Shirley (Tait), a homemaker, and Sewell Mark Gross, a sales executive for AK Steel Holding. Part of his family is originally from Winnipeg, Canada. He was raised a Presbyterian.He moved with his parents to San Francisco in 1954.
Gross is married to Sue J. Gross. They have one child together and Bill has two children from a previous marriage.
Gross graduated from Duke University in 1966 with a degree in psychology. At Duke, he joined Phi Kappa Psi. He then served in the Navy and earned an MBA from the UCLA Anderson School of Management in 1971. Gross briefly played blackjack professionally in Las Vegas, Nevada, and has said that he applies many of his gambling methods for spreading risk and calculating odds to his investment decisions. He is also a CFA Charterholder, earning his credentials while working as an investment analyst for Pacific Mutual Life between 1971 and 1976.
Gross manages one of the world's largest mutual funds, focusing mostly on bonds. Called "the nation's most prominent bond investor" by the New York Times, he co-founded Pacific Investment Management (PIMCO) and currently manages PIMCO's Total Return fund (the world's largest bond fund) and several smaller ones.
In the 1990s he authored two popular-market books on investing, Bill Gross on Investing and Everything You've Heard About Investing is Wrong. In September 2008, by holding large positions in agency backed mortgage bonds of Fannie Mae and Freddie Mac, Gross's funds netted U.S. $1.7 billion after the Federal takeover of Fannie Mae and Freddie Mac for which he had lobbied.
According to Forbes, in 2011, he is the 564th richest person in the world, with a net worth of $2.1 billion.