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D1’s Dan Sundheim on Inspiration From Bezos, Risk Management, Shorting & Career Advice

Reported by Hedgefundalpha
Aug 4, 2025· 2 min read
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Key Takeaways
  • • D1 Capital Partners founder and CIO Dan Sundheim, in an interview with David Rubenstein, described the 2021 GameStop short squeeze as the worst two weeks of his career.
  • • Sundheim spent three years in investment banking at Bear Stearns, including a period in private equity, before joining Viking Global Investors, where he spent 15 years and rose to co-CEO and CIO.
  • • Sundheim founded D1 Capital Partners in 2018, naming the firm after Jeff Bezos's "Day One" philosophy of maintaining entrepreneurial energy and avoiding bureaucracy.
  • • D1, like Viking, relies primarily on fundamental equity research.
Summary
Dan Sundheim, founder and Chief Investment Officer of D1 Capital Partners, discussed his hedge fund career, the firm's investment philosophy and lessons from difficult market cycles in a recent interview with David Rubenstein, according to Hedge Fund Alpha. The most notable lesson he cited was the 2021 GameStop short squeeze, which he described as the worst two weeks of his career.

Sundheim began his investment career after graduating from Wharton. He started in investment banking at Bear Stearns for three years, initially moving into the firm's private equity activity. He then joined Viking Global Investors, a well-known Tiger Cub firm, where he spent 15 years. He described his progression there, saying he started as an analyst covering banks, then picked up every other sector over time before becoming co-CEO and then CIO. Sundheim said Viking, like D1, was primarily focused on fundamental equity research.

In 2018, Sundheim founded D1 Capital Partners. The firm's name draws on Jeff Bezos's "Day One" philosophy for Amazon, which Sundheim adopted to preserve entrepreneurial energy and avoid becoming slow or bureaucratic.

The source material available for this story is limited, and the interview's full discussion of risk management, shorting and career advice is not covered in the text reviewed here.

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Sources

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AlphaMaven summarised this story from the reporting below. Each link opens the original article.

Hedgefundalpha D1’s Dan Sundheim on Inspiration From Bezos, Risk Management, Shorting & Career Advice