Peter attended Babson College in Wellesley, MA and the Berkshire School in Sheffield, MA. He is the son of James Crane Kellogg, III of Wall Street specialist firm Spear, Leeds & Kellogg; he joined his father's firm in 1967 after working at Dominick & Dominick. His fortune is primarily from his successful leadership of Spear, Leeds & Kellogg in the 1980s through to its sale in 2000 to Goldman Sachs for a reported $6.5 billion. Kellogg attended Babson College, but later dropped out.