Dan Sundheim

Dan Sundheim
Born	Daniel Sundheim
Nationality	American
Occupation	Investor, hedge fund manager
Title	Founder and Chief Investment Officer, D1 Capital Partners
Employer	D1 Capital Partners
Known for	Founder of D1 Capital Partners

Daniel Sundheim is an American investor and hedge fund manager who is the founder and chief investment officer of D1 Capital Partners, a New York City-based investment firm that invests in both public and private markets globally. Launched in 2018, D1 Capital Partners grew rapidly to manage approximately US$24 billion in assets by 2022, establishing itself as one of the prominent hedge funds of its generation. Sundheim's career has been marked by both significant gains and notable setbacks, including a roughly $4 billion loss in January 2021 during the GameStop short squeeze, an event he later described as deeply formative in reshaping the firm's risk management practices. Known for a hybrid investment approach that blends traditional long-short equity with significant venture capital and private equity allocations, Sundheim has positioned D1 as a crossover fund that straddles public and private markets. As of early 2026, the firm's private investment portfolio had delivered substantial returns, powered in part by a position in SpaceX that generated an estimated $800 million gain.

Career

Early career and founding of D1 Capital Partners

Prior to founding D1 Capital Partners, Sundheim built a reputation as an investor at other hedge funds, a background that is often associated with the lineage of firms sometimes referred to as "Tiger Cubs" — hedge funds started by or staffed by alumni of Julian Robertson's Tiger Management.

In 2018, Sundheim launched D1 Capital Partners. The fund attracted significant investor interest from its inception, and Sundheim reportedly planned to cap the fund at $4 billion to manage its size and maintain investment flexibility. Despite ambitious beginnings, the fund's early months proved challenging. By late 2018, D1 had experienced losses, reflecting the difficulties of the broader market environment at that time.

The firm established its headquarters in the Solow Building at 9 West 57th Street in New York City, leasing a full floor of office space in one of Midtown Manhattan's premier commercial towers. D1 also later opened an office in Miami, leasing space at 2850 Tigertail Avenue through a deal with the Related Group.

By 2022, D1 Capital had grown to approximately 65 employees and managed roughly $24 billion in assets under management.

Investment strategy and private market ventures

D1 Capital Partners has distinguished itself through a crossover investment strategy, allocating capital to both publicly traded equities and private companies. This hybrid approach placed D1 among a cohort of hedge funds that increasingly participated in late-stage venture capital rounds during the late 2010s and early 2020s.

The firm made a number of high-profile private investments. In 2018, D1 Capital Partners led a $600 million funding round in Instacart, the grocery delivery company, marking one of the firm's first major private market transactions. In 2019, D1 participated in GitLab's $268 million Series E funding round, which valued the software company at $2.768 billion. D1 was also among the investors in Robinhood during its growth phase before the trading platform's initial public offering.

By 2025, the firm's private investment book had become a major contributor to overall returns. In 2025, D1's private portfolio climbed 39 percent, driven significantly by a position in SpaceX, the aerospace company founded by Elon Musk. The SpaceX investment alone was reported to have generated approximately $800 million in gains for the fund.

In October 2025, D1 Capital announced plans to raise more than $1 billion for a new standalone private equity fund, representing a significant expansion of the firm's illiquid investment strategy. The move signaled Sundheim's intention to deepen D1's presence in private markets beyond its existing crossover fund structure.

In the public markets, D1 Capital demonstrated an interest in artificial intelligence-related investments. During the third quarter of 2025, the fund initiated new positions in stocks linked to the AI sector, reflecting a broader thematic investment in the technology trend.

GameStop short squeeze and aftermath

The most widely covered episode in D1 Capital's history occurred in January 2021, during the GameStop short squeeze. As retail investors organized on social media platforms, most notably Reddit's WallStreetBets forum, they drove up the share prices of several heavily shorted stocks, including GameStop Corp. D1 Capital, which held short positions in some of the targeted stocks, suffered losses of approximately 20 percent of its portfolio value in a single month, amounting to roughly $4 billion given the fund's size at the time.

The episode was, by Sundheim's own account, deeply disorienting. In a July 2025 interview with David Rubenstein on Bloomberg Wealth, Sundheim described the experience as "painful" and said it had left him "in a state of shock." However, reporting later indicated that Sundheim credited the GameStop episode as a catalyst for rethinking D1's approach to risk management, positioning decisions, and portfolio construction—changes that he said prepared the firm for subsequent periods of market turmoil.

D1 Capital recovered from the January 2021 losses with relative speed. By April 2021, reporting indicated that the fund had "shaken off" its Reddit-fueled losses and was generating positive returns again.

2022 drawdowns

The year 2022 proved challenging for many hedge funds, particularly those with significant exposure to growth-oriented technology stocks. D1 Capital was among a group of Tiger Cub-linked funds that experienced losses as the stocks that had driven gains in previous years—many in the technology and software sectors—declined sharply amid rising interest rates and a broader market rotation away from high-growth equities.

D1 also faced potential mark-to-market losses on its private investment portfolio, as private company valuations began to decline across the technology sector. Reporting from Bloomberg in mid-2022 noted that D1 could face additional losses as the valuations of private companies in its portfolio came under pressure.

In the wake of the consecutive setbacks of 2021 and 2022, Sundheim made changes to D1's investment process and team. Reporting from Institutional Investor described these adjustments as a response to "two consecutive knockdowns," indicating that Sundheim restructured elements of the firm's operations and investment approach to address the vulnerabilities that had been exposed.

Recovery and 2025 performance

Following the organizational and strategic changes implemented in the aftermath of 2021 and 2022, D1 Capital Partners returned to strong performance. By 2025, the fund was outperforming many of its peers. The firm's public portfolio gained 4.4 percent in April 2025 and was up 11.8 percent for the year through that point, defying broader market headwinds.

Sundheim attributed at least part of D1's improved resilience to the lessons learned during the GameStop episode, telling interviewers that the 2021 crisis had fundamentally reshaped the firm's approach to risk and had prepared it for the market turmoil of 2025.

The private investment portfolio also contributed significantly to the firm's overall performance. As reported in early 2026, the private book gained 39 percent in 2025, driven in large measure by the appreciation in SpaceX, which generated an estimated $800 million gain for the fund.

Charlotte Hornets ownership

In 2023, the NBA Board of Governors approved the sale of the Charlotte Hornets. Sundheim was reported to be among the investor group involved in the transaction.

Public profile

Sundheim has generally maintained a low public profile relative to the scale of assets managed by D1 Capital Partners. However, he participated in a notable public appearance in July 2025 when he sat for an extended interview on Bloomberg Wealth with David Rubenstein. During the conversation, Sundheim discussed his career in hedge fund management, his experience during the GameStop short squeeze, and his investment philosophy.

His career has also been the subject of coverage in The Wall Street Journal, Bloomberg News, the Financial Times, Institutional Investor, and other financial media outlets.