The Largest US Private Foundations (2026): Inside the 5 Percent Payout Rule

Executive Summary

Nearly 90,000 private foundations file with the IRS each year, but fewer than three dozen hold more than $3.5 billion in assets, and that top tier looks more like an institutional endowment desk than a traditional charity. Lilly Endowment is the largest at $105.9 billion, a figure driven almost entirely by its concentrated stake in Eli Lilly stock. The Gates Foundation follows at $78.7 billion. Behind them, Ford, Hewlett, the J. Paul Getty Trust, and Robert Wood Johnson each clear $13 billion, and a deep bench of household-name foundations, Bloomberg, Moore, MacArthur, Mellon, Rockefeller, Walton, sits between $4 billion and $13 billion.

What makes foundations distinct as limited partners is a rule no other major LP type has to answer to. The IRS requires every non-operating private foundation to distribute at least 5 percent of its net investment assets each year, counting grants, program-related investments, and reasonable administrative costs; operating foundations qualify for private-foundation status through a different income and asset test and are generally exempt from this specific floor. Using typical planning assumptions of 2 to 3 percent inflation and roughly a point of management costs, a foundation clearing that payout needs close to 7 to 9 percent annually just to hold its purchasing power flat. That arithmetic is a major reason the largest foundations lean heavily into alternatives: the Council on Foundations-Commonfund Study of Foundations puts private foundations' average allocation to alternative strategies at 45 percent and family foundations' at 52 percent as of year-end 2024, a weighting that increasingly rivals the university endowment model.

This ranking covers private foundations only: entities that file IRS Form 990-PF and are not community foundations, donor-advised-fund sponsors, corporate foundations, hospital or health-system operating charities, or organizations domiciled outside the United States. Several well-known names are excluded on that basis. Howard Hughes Medical Institute is classified by the IRS as a medical research organization, a public charity that files Form 990, not 990-PF. The Chan Zuckerberg Initiative and Jeff Bezos's Earth Fund pledge are structured through LLCs rather than 501(c)(3) foundations, so neither files a 990-PF that discloses total assets. Fidelity Charitable and Schwab Charitable are donor-advised-fund sponsors, public charities with no mandatory payout. Wellcome Trust, Mastercard Foundation, and the INGKA Foundation are large but not US-domiciled.

Every figure below is the foundation's total assets at the end of its most recent tax year, taken from its own IRS Form 990-PF filing, cross-referenced where available against ProPublica's Nonprofit Explorer, which ingests IRS filing data on a lag and may not yet host the most recent year for every foundation. Fiscal years differ across foundations, so the as-of date is shown for each row.

The Largest US Private Foundations by Total Assets

Reading the Table: Structures That Trip Up a Simple Ranking

A handful of the largest foundations are not single, simple entities, and getting the wrong one produces a materially wrong number.

Lilly Endowment's $105.9 billion is a stock story, not a diversification story. The endowment holds the bulk of its assets in Eli Lilly and Company shares, and its total assets nearly doubled between 2023 and 2025, from roughly $62 billion to $105.9 billion, as Lilly's GLP-1 franchise re-rated the stock. That concentration also means the figure can move sharply with the share price in either direction.

"Gates Foundation" is one of two closely related entities, not one. Gates Foundation Trust (EIN 91-1663695) holds and invests the endowment; the Gates Foundation itself (EIN 56-2618866) receives transfers from the Trust and runs the grantmaking. Both filed total assets in the high $70 billions for the same period, $77.6 billion for the Trust and $78.7 billion for the operating Foundation, and press coverage typically cites the operating Foundation entity. They are not separate philanthropies that sum to $150 billion or more; this ranking uses the operating Foundation figure.

The Carl Victor Page Memorial Foundation, Larry Page's private foundation, is not a $100 billion entity, despite estimates that have circulated online. Its FY2024 Form 990-PF reports total assets of $4.5 billion, up from $4.0 billion the prior year. Widely cited larger figures are not supported by the foundation's own IRS filings, which are the primary source of record.

W.K. Kellogg is split across a Trust and a Foundation. The W.K. Kellogg Foundation Trust holds the corpus, roughly $9.0 billion, while the operating W.K. Kellogg Foundation reports around $450 million in its own name. This ranking uses the Trust, which holds the overwhelming majority of the combined assets.

Open Society Foundations is a brand for a multi-entity network. The Foundation to Promote Open Society is the largest and most active current grantmaking vehicle, with total assets of $10.8 billion, and is what this ranking uses. A separate, smaller entity, Open Society Institute, holds roughly $5.3 billion and is not summed with the first to avoid double-counting related transfers.

Duke Endowment's Form 990-PF reports total assets on a cost basis, not fair market value. Its 990-PF shows $3.6 billion; the Endowment's own audited financial statements report $5.0 billion in total assets at fair market value for the same date. This ranking uses the 990-PF figure for consistency with every other row, since it is the one basis every private foundation reports on the same form.

Two large, well-known organizations are deliberately absent. Howard Hughes Medical Institute holds roughly $29.5 billion but is IRS-classified as a medical research organization, a type of public charity that files Form 990 rather than 990-PF; it does not carry the 5 percent private-foundation payout requirement this ranking is built around. Susan and Bill Gates's foundation aside, a number of foundations in the next tier, Sloan, Rockefeller Brothers Fund, Surdna, Doris Duke, and others, hold $1 billion to $3 billion and did not clear the cutoff for this list.

Why the 5 Percent Rule Drives Foundation Allocations

Every other major institutional LP type, pensions, endowments, insurers, chooses its own payout policy or answers to an actuarial funding target. Non-operating private foundations answer to a fixed federal minimum under IRC Section 4942: 5 percent of net investment assets, distributed annually, or face an excise tax on the shortfall. Operating foundations qualify for private-foundation status through a different route, an income test paired with an assets, endowment, or support test, and are generally exempt from this 5 percent minimum-distribution rule in favor of a direct-spending requirement tied to adjusted net income. For a non-operating foundation, the payout is not a soft target. It is a statutory floor that has to be cleared through market cycles, including down years.

The arithmetic behind that rule is what pushes foundation portfolios toward private markets. Using typical planning assumptions, the 5 percent payout plus 2 to 3 percent inflation and roughly a point of management costs, a foundation needs to generate 7 to 9 percent annually just to keep its real purchasing power flat, let alone grow, a bar public fixed income has struggled to clear on its own. The result: private foundations run close to half their portfolios in alternative strategies. The Council on Foundations-Commonfund Study of Foundations puts the average private foundation's allocation to alternative strategies, private equity, venture capital, marketable alternatives, and real assets, at 45 percent as of year-end 2024, with family foundations running higher at 52 percent. Academic research covering private foundation IRS filings from 1991 to 2020 documents the same directional shift: foundations' combined equity-and-alternatives weighting rose from about 40 percent in 1990 to nearly 80 percent by 2020 as government-debt holdings fell from nearly 20 percent to about 2 percent. That weighting increasingly rivals the allocations at the largest university endowments.

Three things follow for a GP evaluating foundations as a source of capital:

The payout creates a structural liquidity and return need, not a mandate to keep committing to new funds. Meeting the distribution requires generating enough distributable cash and portfolio return every year, in every market environment, which is what keeps private-markets exposure a permanent feature of the portfolio rather than a discretionary allocation. That translates into steady rebalancing and reinvestment as older vintages mature and distribute, but it does not obligate a foundation to commit to any specific new fund.

Mission alignment is a real screen, not a marketing layer. Ford's $1 billion mission-related investment program, MacArthur's $390 million impact portfolio, and Kresge's commitment to fund 25 percent of its US assets with female- and diverse-owned managers are not side initiatives, they sit inside the same investment committee that approves traditional commitments. A strategy that maps to a foundation's program area has a real edge in diligence.

Concentrated stock risk defines several of the largest names. Lilly Endowment's assets are still dominated by a single stock. That concentration cuts both ways for a GP: it explains why the endowment's total-assets figure can swing sharply, and it means its actual deployable, diversified capital pool is smaller than the headline number suggests.

How GPs Engage Foundation LPs

Foundation investment offices are small, typically ranging from a handful of professionals at the smaller end of this list to several dozen at Gates or Ford, and they run concentrated manager rosters. They are closer to endowments than to pensions in how they select managers: relationship-driven, reference-heavy, and slow to add a new name, but durable once a commitment is made.

Three things matter more with foundations than with a large public pension. First, the mission and program areas are public and specific, published on every foundation's own site, so a GP whose strategy genuinely intersects with a foundation's focus area (healthcare, climate, education, economic mobility) starts the conversation from a stronger position than a generic pitch. Second, foundation boards and investment committees meet on a fixed calendar, and new manager additions are rationed, so timing an approach around a foundation's own pacing matters as much as the pitch itself. Third, many of the largest foundations disclose their 990-PF filings, including grants and, in some cases, investment managers, which gives a prepared GP a way to see who a foundation already backs before reaching out cold.

Most outreach to foundations treats them like a generic LP list. The funds that actually get commitments research the program fit first, work through a warm introduction from an existing manager or trustee, and time the approach to the foundation's own pacing rather than the fund's own calendar.

For the full institutional universe, including pensions, endowments, insurers, and family offices alongside these foundations, see the investor directory and the foundations directory specifically, which profiles foundations by their alternatives allocation and investment focus rather than by asset size. For how a primary-source raise is run, see fundraising and capital formation.

Sources & Methodology

Each figure is the foundation's total assets at the end of its most recent tax year, taken from its own IRS Form 990-PF filing, cross-referenced where available against ProPublica's Nonprofit Explorer, which ingests IRS filing data on a lag. Fiscal years differ by foundation, so the as-of date is shown for each row. Scope is limited to organizations that file Form 990-PF as private foundations (non-operating or operating), are domiciled in the United States, and are not community foundations, donor-advised-fund sponsors, corporate foundations, or hospital and health-system operating charities. Where a foundation operates through related entities (Gates Foundation Trust and Gates Foundation; the W.K. Kellogg Foundation and its Trust; the Open Society network), the entity holding the majority of assets and most closely matching common usage is used, with the relationship disclosed above. Duke Endowment is shown on its 990-PF cost basis ($3.6 billion) rather than its audited fair-market-value basis ($5.0 billion) for consistency with every other row.

Primary sources (ProPublica Nonprofit Explorer, EIN in parentheses): Lilly Endowment (35-0868122), Gates Foundation (56-2618866), Ford Foundation (13-1684331), Hewlett Foundation (94-1655673), J. Paul Getty Trust (95-1790021), Robert Wood Johnson Foundation (22-6029397), Bloomberg Family Foundation (20-5602483), Gordon and Betty Moore Foundation (94-3397785), Foundation to Promote Open Society (26-3753801), MacArthur Foundation (23-7093598), W.K. Kellogg Foundation Trust (36-6030614), Packard Foundation (94-2278431), Andrew W. Mellon Foundation (13-1879954), Michael & Susan Dell Foundation (36-4336415), Conrad N. Hilton Foundation (94-3100217), Rockefeller Foundation (13-1659629), Walton Family Foundation (13-3441466), Carnegie Corporation of New York (13-1628151), Simons Foundation (13-3794889), The California Endowment (95-4523232), Carl Victor Page Memorial Foundation (20-1922957), Kresge Foundation (38-1359217), Charles Stewart Mott Foundation (38-1211227), John Templeton Foundation (62-1322826), Duke Endowment (56-0529965). Payout-rule context draws on IRC Section 4942 and IRS guidance on private-foundation minimum-distribution requirements. Alternatives-allocation context draws on the 2024 Council on Foundations-Commonfund Study of Foundations (data as of Dec 31, 2024) and Binfare and Zimmerschied, "Investing with Purpose: Evidence from Private Foundations," Journal of Finance (IRS filings, 1991 to 2020).