JPMorgan Chase CEO Jamie Dimon says his finance career began in childhood, shaped by hours spent playing investment simulation games with his father in a hands-on lesson about how to value a business.

“He would give me an industry you might know something about, like a restaurant,” Dimon said on a recent episode of The Master Investor Podcast with Wilfred Frost. “And say, ‘Okay, look at this. Look at the history. Read the annual report. Study the industry if you want. What would you pay for the stock?”

Dimon said the exercise became a foundational part of his thinking. Now 70, he has led JPMorgan Chase for nearly two decades and built it into the largest bank in the U.S., but he said his instinct for pricing a business started long before business school.

His father, Theodore, was a Wall Street stockbroker who encouraged all three of his sons to learn about the markets, though Dimon said only he fully embraced the lessons. While his brothers showed little interest, Dimon gravitated toward large business decisions and used the simulation games to learn the basics of stock picking and decision-making.

“It is brutally hard,” Dimon said. “Then you learn the ‘why.’”

By high school, Dimon said he was already reading widely on finance and related subjects. He spent his spare time on books, papers, and reports covering psychology, economics, and accounting.

“I read Graham and Dodd in high school—I was a nerd,” Dimon said. “I read all of Freud’s books. I always would be taking this stuff in.”

Dimon bought his first stock at age 14 in 1970, with guidance from his father, and has said he never looked back. He later graduated from Tufts University and earned an MBA from Harvard Business School.

After graduate school, Dimon took his first Wall Street job as an assistant to then-American Express president Sanford “Sandy” Weill. In a 1984 Fortune profile, the 28-year-old Dimon said, “My first goal was to learn something and not say anything until I could add some value.”

The apprenticeship under Weill became, in Dimon’s words, his real business school. He joined Weill as his assistant at American Express in 1982, and when the two left to take over consumer lender Commercial Credit in 1986, Dimon became chief financial officer at age 30. Under Weill’s mentorship, he learned the inner workings of banking, a foundation that later led to senior roles at Citigroup and Bank One. Bank One merged with JPMorgan Chase in 2004, and two years later, in 2006, Dimon became CEO of JPMorgan Chase.

Today, Dimon is one of the few Wall Street CEOs still in place from the 2008 financial crisis. He has led JPMorgan for nearly two decades, making him an outlier among peers whose tenures typically lasted less than a decade, according to Esgauge data. The bank is now the largest in the U.S. and ranks No. 12 on the Fortune 500 and No. 19 on the Global 500.

In 2025, JPMorgan generated $185.6 billion in revenue, up $5 billion from the year before, according to the company’s 2025 annual report. Dimon’s personal wealth has also grown substantially; Bloomberg’s Billionaire’s Index puts his net worth at $3.2 billion.

When asked whether he always believed he would lead JPMorgan Chase to a market capitalization approaching $1 trillion, Dimon answered: “No.”

Instead, he described a philosophy based more on discipline than on ambition. Although his early interest in finance came from his father, Dimon said his approach is inspired by elite athletes as much as by Wall Street peers.

“I think you get in trouble if you say, ‘I want to be the biggest bank in the world,’” Dimon said, citing NFL quarterbacks Tom Brady and Peyton Manning. “They say they didn’t have the best arm and they weren’t good runners, but they became the best.”

He has made a similar point before. At the Fortune Most Powerful Women Summit in 2025, Dimon told Fortune Editor-in-Chief Allyson Shontell that he gives 100% effort “every day, every meeting.” He said success requires steady work and humility.

“You can’t hit a home run every time you’re at the bat,” Dimon told Shontell. “You keep working, stay humble, and work hard.”

It is the same lesson his father taught him more than half a century ago over annual reports and investment games: do the work, and understand the why.

This story was originally featured on Fortune.com