Bill Ackman said two early experiences were decisive in his rise as an investor: a commission-based advertising job at Harvard that earned him $14,000 and a recommendation to read Ben Graham’s The Intelligent Investor. Speaking on Fortune’s Titans and Disruptors of Industry podcast, Ackman said the student sales role gave him his first real business success, while the book helped steer him toward value investing, an approach closely associated with Warren Buffett, whom Ackman described as an unofficial mentor. After completing his MBA at Harvard Business School in 1992, Ackman co-founded Gotham Partners with David Berkowitz and later launched Pershing Square Capital Management in 2004. The New York-based hedge fund now oversees $35 billion. Ackman said he has also tried to emulate Berkshire Hathaway’s permanent-capital model by taking Pershing Square public, a structure that lets investors trade shares with each other rather than redeeming directly from the fund, helping keep capital invested over time.