Dan Sundheim

Background

Dan Sundheim is the Founder and Chief Investment Officer of D1 Capital Partners, a global investment firm he established in July 2018 ¹². D1 operates across both public and private markets, combining what Sundheim describes as “the talent and operational excellence of a large, premier asset management firm with the flexible mandate and long-term time horizon of a family office” ¹.

Sundheim was born outside Philadelphia and grew up around stocks, influenced by his father’s interest in investing despite his father being a doctor and his mother an occupational therapist ³. He earned a B.S. in Economics from the Wharton School at the University of Pennsylvania in 1999 ¹⁴.

His career began in the Merchant Banking Group at Bear Stearns, where he researched and executed private equity investments ¹⁴. He then joined Viking Global Investors in 2002, the Tiger Cub hedge fund founded by Ole Andreas Halvorsen ²⁵. Sundheim spent 15 years at Viking, starting as an analyst covering banks and over time expanding to cover every sector ³. He took over co-CIO responsibilities in 2010 after the departure of Viking co-founder David Ott, and became sole CIO ²⁵. He left Viking on June 30, 2017, prompting the firm to return $8 billion to investors ⁵.

To launch D1 Capital Partners, Sundheim invested more than $500 million of his own capital ². The firm’s name was inspired by Jeff Bezos’s “Day One” philosophy for Amazon, reflecting a desire to maintain entrepreneurial energy ². D1 originally managed approximately $3 billion and grew to $20 billion in assets by the end of 2020, with annualized returns of nearly 30% ². As of March 2024, D1 managed approximately $26 billion across 42 clients ⁶. The firm’s Q4 2025 13F filing showed approximately $10.7 billion in U.S.-listed public equity holdings across 42 positions, with additional private portfolio holdings ⁷.

D1 experienced significant losses during the January 2021 meme stock short squeeze, losing approximately 30% of its public portfolio ²⁸. In 2022, the firm lost 34% overall, with public investments falling 44% and private investments marked down 15.7% ²⁸. Following these setbacks, Sundheim restructured the fund’s risk management in June 2022, reducing gross exposure from 218% to 165%, cutting net exposure from 67% to 28%, and expanding stock coverage from approximately 600 to 800+ names ². Since the restructuring, D1’s public portfolio has delivered strong performance: up 19% in 2023, 44% in 2024, and compounding at a 33% net annualized rate ²⁹.

Private investments constitute approximately 60% of D1’s total assets, with high-profile holdings including SpaceX, Collectors Holdings, Lineage, and Ramp ⁸⁹. In 2025, D1 began raising its first dedicated private equity fund, targeting over $1 billion and securing $1.5 billion in commitments largely from existing investors ⁹.

Sundheim is a minority owner of the Charlotte Hornets, having acquired a stake alongside Gabe Plotkin in 2019 at Michael Jordan’s invitation ²¹⁰. He serves on the Board of Trustees of the Museum of Modern Art (MoMA), NYU Langone Medical Center, and Columbia Grammar and Preparatory School ¹. He also serves on the Board of Directors of Instacart (Maplebear Inc.), having joined the board in June 2020 ⁴. His net worth is estimated at approximately $2.6 billion ¹¹.

Stated Thesis

(Self-reported: These represent what Sundheim says publicly about his approach. See Inferred Thesis for analysis of actual investment behavior.)

Sundheim describes D1’s approach as rooted in fundamental analysis with a long time horizon. He has stated: “We invest in public and private companies. We do fundamental analysis, and so deep research, trying to understand business models” ³. He views investing as pattern recognition developed over decades: “It’s an art, not a science” ³.

D1 focuses on sectors including global internet, technology, telecom, media, consumer, healthcare, financial, industrial, and real estate ¹. Sundheim has emphasized the importance of holding winners rather than trading, noting that the biggest mistakes come from selling great companies too early ³.

Sundheim has expressed a strong preference for private markets over public markets for high-quality companies. He has stated that if he ran a private company like Stripe, he would not go public, calling today’s public market structure “problematic” ³. He has praised Elon Musk’s cost-focused approach to business, stating that Musk “just naturally understands — just get the cost down, get the cost down, get the cost down, and that’s very hard to compete against” ³.

On short selling, Sundheim has stated that the opportunity is better than ever in his career, but that position sizing and risk management must be paramount ³. Following the 2021 meme stock losses, he restructured D1’s approach: “Risk management has to happen before the fact, meaning you size these positions so that when it goes up, you don’t have to cover” ³.

Sundheim has described D1’s geographic focus as primarily North America (65%) and Europe (30%), and has stated he stopped investing in China approximately three years ago, citing excessive government influence on resource allocation ²³.

Inferred Thesis

Based on 42 verified public equity positions (Q4 2025 13F) and approximately 14 verified private investments:

Investment style: D1 is a crossover fund — a hybrid between a traditional long/short equity hedge fund and a late-stage growth equity investor. Sundheim personally makes most trading decisions and reads earnings in the middle of the night due to European market exposure ³⁶. This is not a typical venture firm; D1 makes concentrated, large-dollar bets in both public and private markets with a 3-5 year horizon.

Stage distribution: D1 operates primarily at the growth and late-stage end of the spectrum. In public markets, positions range from $16 million (Medline Industries) to over $1 billion (Maplebear/Instacart) ⁷. In private markets, D1 has invested in companies at valuations ranging from $36 billion (SpaceX in early 2020) to pre-IPO rounds of companies like Ramp ($1.6 billion valuation in 2021), and has participated in rounds as large as Anthropic’s $3.5 billion raise ¹²¹³. D1 is not a seed or early-stage investor.

Public portfolio sector concentration (42 positions, Q4 2025 13F) ⁷: - Technology & software: 10 of 42 positions (24%) — NVDA, META, AMZN, SPOT, SNPS, ADSK, ANET, AVGO, TXN, APP - Industrials & infrastructure: 9 of 42 positions (21%) — FLS, JHX, KNX, XPO, LIN, JCI, CNM, APG, LINE - Consumer & commerce: 6 of 42 positions (14%) — CART, RDDT, SE, MELI, DIS, USFD - Financials: 5 of 42 positions (12%) — SCHW, COF, APO, BAC, AFRM - Healthcare: 3 of 42 positions (7%) — GEHC, DHR, MDLN - Environmental services: 1 of 42 positions (2%) — CLH - Real estate: 1 of 42 positions (2%) — KRC - Utilities & other: 4 of 42 positions (10%) — NI, AEP, SATS, SHW - Other: 3 of 42 positions (7%) — ENTG, Q, PURR

Private portfolio composition (verified investments): D1’s private portfolio is heavily concentrated. SpaceX alone accounts for roughly 45% of private equity exposure, with the stake valued at approximately $2.5 billion ⁹. Other major private holdings include Collectors Holdings, Lineage (now public as LINE), Ramp, Anthropic, OpenAI, Instacart (now public as CART), Hadrian, Ualá, and Stripe ^391213141516.

Key patterns:

Concentration risk tolerance: Sundheim runs a highly concentrated portfolio. His top 10 public positions account for 75% of the 13F portfolio ⁷. In private markets, SpaceX alone represents nearly half of private exposure ⁹. This is consistent with his stated philosophy of holding winners.

European turnaround bets: D1 has allocated approximately 30% to European markets ². Sundheim wakes at 3 AM daily for European market openings ³. Notable European winners include Siemens Energy and Rolls-Royce Holdings, which Sundheim described as having “good technology” that was “very, very poorly managed” ²³.

AI infrastructure conviction: D1 has backed both OpenAI and Anthropic — the two leading frontier AI companies — along with public AI-linked positions in NVDA, AVGO, and APP ¹²¹⁵²¹. This dual-bet approach suggests conviction in the AI infrastructure category rather than a single company.

Crossover advantage: D1’s ability to invest across public and private markets gives it a distinctive position. The firm took Collectors Universe private in a $700 million deal in 2020, held Instacart pre-IPO and maintained its position post-IPO (CART is now D1’s largest public holding at $1 billion), and invested in Lineage pre-IPO before it became the largest IPO of 2024 ⁴⁷¹⁷¹⁸.

Fintech thread: Across both public and private portfolios, fintech is a recurring theme: Ramp (corporate cards), Ualá (Latin American neobank), Stripe, Affirm (AFRM), Capital One (COF), Charles Schwab (SCHW), and Apollo Global Management (APO) ^7131516.

Notable gaps: Despite D1’s massive scale, the firm does not invest at seed or Series A stages. D1 is not a venture capital firm in the traditional sense — it is a crossover hedge fund that makes growth-stage private investments and large public market bets. Founders seeking early-stage capital would not approach D1.

Portfolio

Private Investments

Public Equity Holdings (Q4 2025 13F) ⁷

Historical Performance ²⁸

In Their Own Words

On his investment approach: “We invest in public and private companies. We do fundamental analysis, and so deep research, trying to understand business models.” — Dan Sundheim, Cheeky Pint podcast ³

On investing as craft: “It’s an art, not a science.” — Dan Sundheim, Cheeky Pint podcast ³

On holding winners: “The biggest mistakes are selling the Costcos too early because the IRR is totally dependent upon what you assume the exit multiple is.” — Dan Sundheim, Cheeky Pint podcast ³

On being wrong: “I am wrong all the time, even when I’ve done a ton of work.” — Dan Sundheim, Cheeky Pint podcast ³

On the January 2021 meme stock losses: “I was almost in shock. We were losing an amount of money that was almost hard to even fathom.” — Dan Sundheim, Cheeky Pint podcast ³

On risk management lessons: “Risk management has to happen before the fact, meaning you size these positions so that when it goes up, you don’t have to cover.” — Dan Sundheim, Cheeky Pint podcast ³

On short selling: “I like shorting stocks. It’s masochistic, but I love doing it.” — Dan Sundheim, Cheeky Pint podcast ³

On multiple expansion: “You do make most of your money on multiple expansion. The multiple over the long term is a function of the perception of stability of the cash flows over the long term.” — Dan Sundheim, Cheeky Pint podcast ³

On Elon Musk and SpaceX: “I think he’s a better business person than he is an inventor. He’s amazing at both. He just naturally understands — just get the cost down, get the cost down, get the cost down, and that’s very hard to compete against.” — Dan Sundheim, Cheeky Pint podcast ³

On public markets for private companies: “If I ran a private company like Stripe, I wouldn’t go public. I think the public markets are kind of problematic at this point.” — Dan Sundheim, Cheeky Pint podcast ³

On Rolls-Royce as a turnaround: “Rolls-Royce actually had good technology. It was just very, very poorly managed.” — Dan Sundheim, Cheeky Pint podcast ³

On why D1 stays away from China: “The government has way too much influence on how resources are allocated. Markets don’t like uncertainty.” — Dan Sundheim, Cheeky Pint podcast ³

On his daily routine: “Without an alarm clock, I will wake up almost exactly between 2:55 and 3:00 AM almost every day.” — Dan Sundheim, Cheeky Pint podcast ³

On D1’s Ramp investment: “Ramp has quickly become a key player in the financial services ecosystem by challenging business practices and assumptions that have existed for nearly 50 years.” — Dan Sundheim, Ramp press release, April 2021 ¹³

On SpaceX’s valuation surge: Sundheim described SpaceX’s recent valuation increase to an estimated $800 billion as a reflection of “transformational progress” across its core businesses, and stated that the firm believes SpaceX could ultimately become the single largest driver of value creation within D1’s portfolio ⁹.

What Founders Say

Keith Rabois, Founders Fund Partner, stated in Ramp’s Series B announcement: “Like Square, Paypal, and Stripe, Ramp is rapidly emerging as a generational fintech company…Ramp is already viewed as the obvious choice for efficient spend management” ¹³. While not a direct testimonial about D1, this appeared in a round that D1 co-led, indicating co-investor confidence in D1’s deal selection.

No independently sourced founder testimonials specifically about working with Dan Sundheim or D1 Capital Partners were found. As a crossover hedge fund rather than a traditional venture firm, D1’s relationship with portfolio company founders differs from typical VC-founder dynamics. Sundheim serves on the board of Instacart (since June 2020) and holds board seats at several other D1 portfolio companies ⁴, suggesting active involvement, but public founder commentary on D1’s value-add as an investor could not be independently verified.

Sources