Tandem Philanthropies FKA the Ark Foundation
Tandem Philanthropies is a private foundation based in Menlo Park, California. Its 2024 filing reports grants to charitable organizations in education, energy, climate and sustainability, and health care-related environmental work.
Tandem Philanthropies FKA the Ark Foundation at a glance
In short: Tandem Philanthropies FKA the Ark Foundation gave $3.9M across 11 grants in 2024 (avg $350K), top state California. Source: 2024 IRS Form 990-PF.
- Annual giving (2024)
- $3,850,000
- +40.0% vs 2023
- Grants made (2024)
- 11
- +37.5% vs 2023
- Average grant
- $350,000
- +1.8% vs 2023
- Median grant
- $350,000
- Total assets
- $74,004,281
- +7.7% vs 2023
- Primary geography
- California (45% of itemized 2024 grant dollars)
- Latest 990 filing
- Form 990-PF, 2024 View filing
Data from IRS Form 990-PF, 2024; updated October 2026.
How to apply to Tandem Philanthropies FKA the Ark Foundation
- Accepts unsolicited proposals
- No
- How to Apply
-
The foundation makes contributions only to preselected charitable organizations and does not accept unsolicited requests for funds.
- Contact
Mailing address: 1550 El Camino Real 200, Menlo Park, CA 94025
Phone: (650) 289-1110
Application details from Grantable's research on the foundation's public materials; confirm on its website before applying.
Who Tandem Philanthropies FKA the Ark Foundation funds
How this funder distributes its grants
Top Recipients
Top 10 recipients in 2024
The largest 2024 recipient was United States Energy Foundation ($750K). Together the top 10 received $3.8M.
Grant Size Distribution
26 grants across all recorded years
The most common grant size was in the $250–500K range: 10 grants of 26 (38%).
Geographic Focus
Where this funder awards grants
In 2024, grant dollars went to recipients in California (45%), New York (16%), Arizona (13%), Massachusetts (13%), and Virginia (13%).
Grant Distribution by State
Share of 2024 grant dollars across all 11 itemized grants.
Cities
How Tandem Philanthropies FKA the Ark Foundation gives
- 55% of 2024 grantees were also funded in 2023. Method
- Giving grew 157% from 2021 to 2024. Method
- In 2024 it paid out 118% of its IRS minimum distribution (the 5% rule). Method
Estimate from itemized grant lists in IRS Form 990-PF filings (2024). Recipient names are matched across years, so a renamed or misspelled grantee can look new; grants to individuals are left out. Methodology.
Giving History
Giving Over Time
Total grant dollars and number of grants per year
From 2020 to 2024, annual grant giving ranged from $1.1M (2020) to $3.9M (2024). In 2024 it made 11 grants totaling $3.9M.
Grants by year
Grant recipients and amounts by year
| Recipient | Purpose | Amount |
|---|---|---|
| United States Energy Foundation San Francisco, CA | To Provide General Support | $750,000 |
| Arizona State University Foundation Tempe, AZ | To Provide General Support | $500,000 |
| Ceres Boston, MA | To Provide General Support | $500,000 |
| Health Care Without Harm Reston, VA | To Provide General Support | $500,000 |
| Silicon Schools Fund Inc Oakland, CA | To Provide General Support | $500,000 |
| Educators for Excellence Inc New York, NY | To Provide General Support | $350,000 |
| Transcend Inc Hastings on Hudson, NY | To Provide General Support | $250,000 |
| Alder Graduate School of Education Redwood City, CA | To Provide General Support | $200,000 |
| Bay Education Fund Oakland, CA | To Provide General Support | $100,000 |
| Edvoice Institute Sacramento, CA | To Provide General Support | $100,000 |
Ready to take the next step with Tandem Philanthropies FKA the Ark Foundation?
Financial History
Multi-year comparison from IRS filings
| Filing year | Total Assets | Revenue | Expenses | Grants paid | Grants | Qualifying Distributions | Net Investment Income | Distributable Amount |
|---|---|---|---|---|---|---|---|---|
| 2024 | $74,004,281 | $13,637,360 | $4,502,886 | $3,850,000 | 11 | $4,124,605 | $10,031,685 | $3,486,962 |
| 2023 | $68,741,470 | $47,099,817 | $3,248,283 | $2,750,800 | 8 | $2,947,283 | $36,181,565 | $2,473,421 |
| 2022 | $32,930,878 | $4,858,810 | $1,234,371 | $1,150,000 | 5 | $1,210,900 | $1,238,863 | $2,558,747 |
| 2021 | $32,913,045 | $39,564,064 | $1,588,526 | $1,500,000 | 1 | $1,547,665 | $2,446,954 | $1,525,258 |
| 2020 | $21,621,531 | $1,291,700 | $1,109,303 | $1,080,000 | 1 | — | $692,088 | $1,106,761 |
Under IRS private-foundation payout rules, Tandem Philanthropies FKA the Ark Foundation reported a distributable amount of $3.5M for 2024 — the minimum it must pay out in qualifying distributions.
Research compiled by Grantable AI from public sources. Last updated September 2026.
Mission & Focus Areas
No foundation mission statement is provided. Its 2024 grants included support for organizations working in several areas. The United States Energy Foundation describes its mission as securing a clean and equitable energy future to tackle the climate crisis. Health Care Without Harm says it works to transform health care worldwide to reduce its environmental footprint and advance environmental health and justice.
Education grantees describe varied missions: Silicon Schools Fund supports the launch of new schools, improvement of instruction, and education innovation; Transcend supports communities to create and spread extraordinary learning for all; and Alder Graduate School of Education recruits and educates teachers and leaders who reflect their schools’ communities. New Schools Fund says it identifies and supports promising education ventures and builds a network of education entrepreneurs committed to closing the achievement gap.
Grantmaking
In 2024, the foundation made 11 grants totaling $3,850,000. Grant amounts ranged from $100,000 to $750,000, with a median of $350,000. All listed 2024 grants were for general support.
Largest 2024 grants included $750,000 to United States Energy Foundation; $500,000 each to Arizona State University Foundation, Ceres, Health Care Without Harm, and Silicon Schools Fund; and $350,000 to Educators for Excellence. Other grants included $250,000 to Transcend, $200,000 to Alder Graduate School of Education, and $100,000 each to Bay Education Fund, EdVoice Institute, and New Schools Fund.
Leadership & Key People
Leadership team and compensation from IRS filings
The 2024 filing lists David L. Sze as director, secretary, and CEO; Kathleen M. Donohue as director and CFO; and Zachary Herlick as audit committee member.
Tandem Philanthropies FKA the Ark Foundation is led by David L. Sze, Director, Secretary & CEO since 2023 (on filings since 2020); none of the 3 officers listed in 2024 report compensation.
Officers on the 2024 filing
David L. Sze
Director, Secretary & CEO
Director, Secretary & C → Director, Secretary & CEO, 2023
On filings since 2020
0.8 hrs/week
No compensation reported
Kathleen M. Donohue
Director & CFO
On filings since 2020
0.8 hrs/week
No compensation reported
Zachary Herlick
Audit Committee Member
On filings since 2020
2 hrs/week
No compensation reported
Data from IRS Form 990 filings, 2020–2024. "On filings since" is the earliest filing we hold that lists the person; hours are average hours per week as reported.
Frequently asked questions about Tandem Philanthropies FKA the Ark Foundation
How much does Tandem Philanthropies FKA the Ark Foundation give each year?
Tandem Philanthropies FKA the Ark Foundation gave $3.9M across 11 grants in 2024, according to its 2024 IRS Form 990-PF. In 2023 it gave $2.8M across 8 grants.
What is Tandem Philanthropies FKA the Ark Foundation's typical grant size?
Tandem Philanthropies FKA the Ark Foundation's median grant in 2024 was $350,000, and its average grant was $350,000, across 11 grants on its 2024 IRS Form 990-PF.
Where does Tandem Philanthropies FKA the Ark Foundation give grants?
Tandem Philanthropies FKA the Ark Foundation's top state is California, with 45% of the grant dollars itemized on its 2024 IRS Form 990-PF. The next largest states were New York (16%) and Arizona (13%). The most frequent recipient cities were Oakland, CA (3 grants).
Does Tandem Philanthropies FKA the Ark Foundation give general operating support?
Yes: 100% of Tandem Philanthropies FKA the Ark Foundation's 2024 grants with a stated purpose (11 of 11) were for general or operating support, per its 2024 IRS Form 990-PF.
Who are Tandem Philanthropies FKA the Ark Foundation's largest grantees?
Tandem Philanthropies FKA the Ark Foundation's largest 2024 grantees include United States Energy Foundation ($750,000), Arizona State University Foundation ($500,000) and Ceres ($500,000), according to its 2024 IRS Form 990-PF. Together they received 45% of its itemized 2024 grant dollars.
How large is Tandem Philanthropies FKA the Ark Foundation?
Tandem Philanthropies FKA the Ark Foundation reported $74.0M in total assets on its 2024 IRS Form 990-PF. It paid out $4.1M in qualifying distributions that year, against a required minimum of $3.5M (roughly 5% of its investment assets).
What does Tandem Philanthropies FKA the Ark Foundation fund?
No foundation mission statement is provided. Its 2024 grants included support for organizations working in several areas. The United States Energy Foundation describes its mission as securing a clean and equitable energy future to tackle the climate crisis. See mission & focus areas ↑
How do I apply for a grant from Tandem Philanthropies FKA the Ark Foundation?
The foundation makes contributions only to preselected charitable organizations and does not accept unsolicited requests for funds. Eligibility and process details are in the grantmaking section of this profile. See how to apply ↑
What is Tandem Philanthropies FKA the Ark Foundation's EIN?
Tandem Philanthropies FKA the Ark Foundation's EIN (Employer Identification Number) is 38-4055324. IRS Form 990 filing data is available on this page for 2020–2024.
Does Tandem Philanthropies FKA the Ark Foundation accept unsolicited proposals?
No, according to Grantable's research on the foundation's published guidelines. See how to apply ↑
Data last updated October 2026. Sourced from IRS Form 990-PF filings. Research dossier generated September 2026.
Data update history
(6)
When this profile's IRS filing data changed on Grantable
- Updated Form 990-PF for fiscal year 2020 (received by the IRS November 15, 2021)
- Updated Form 990-PF for fiscal year 2021 (received by the IRS November 10, 2022)
- Updated Form 990-PF for fiscal year 2022 (received by the IRS November 14, 2023)
- Updated Form 990-PF for fiscal year 2023 (received by the IRS November 7, 2024)
- Updated Form 990-PF for fiscal year 2024 (received by the IRS November 17, 2025)
- IRS filings on file for fiscal years 2020–2024
Live grants for the work Tandem Philanthropies FKA the Ark Foundation funds
Philanthropy, Voluntarism & Grantmaking Open opportunities, soonest deadline first.
Explore Open Grants
Browse active grant opportunities in Tandem Philanthropies FKA the Ark Foundation's focus areas in our free grants database
Similar Funders
Funders that support many of the same organizations
Silicon Valley Community Foundation
Mountain View, CA
Silicon Valley Community Foundation funds work in areas such as housing, economic security, education, health, the environment, arts and culture, and civic engagement, with Community Action Grants supporting local, community-led organizations in San Mateo and Santa Clara counties. Its 2024 grants had a median of $51,716, though amounts varied widely; applications depend on the program, and SVCF states that it does not accept unsolicited proposals for advised funds.
Assets
$12.3B
Grants
3,576
Total Given
$3.2B
Walton Family Foundation Inc
Bentonville, AR
The Walton Family Foundation funds K–12 education, river and ocean conservation, and quality-of-life initiatives in Northwest Arkansas and the Arkansas-Mississippi Delta; its grants also support organizations and projects elsewhere in the U.S. Its 2024 grants had a median of $200,000, with awards ranging from $1,000 to $35.6 million. It does not accept unsolicited requests except from eligible public charter school developers applying to its startup grant program; other organizations must first submit a letter of inquiry and await an invitation.
Assets
$6.1B
Grants
1,020
Total Given
$562.3M
The William & Flora Hewlett Foundation
Menlo Park, CA
The William & Flora Hewlett Foundation funds education, climate and conservation, the arts, democracy, gender equity, racial justice, and efforts to strengthen nonprofits and philanthropy, with work spanning the San Francisco Bay Area, the U.S. West, and locations including East and West Africa and Mexico. Its 2024 grants had a median award of $150,000, though amounts varied widely. It generally does not accept unsolicited requests, but sometimes invites proposals through open processes.
Assets
$14.2B
Grants
2,001
Total Given
$625.0M
Boston Foundation Inc
Boston, MA
The Boston Foundation funds nonprofits and community initiatives focused on equity and opportunity, including child well-being, economic opportunity, community wealth, and community leadership, primarily in Greater Boston. Its 2025 grants had a median of $25,000, while specific programs offer amounts such as $50,000; whether it accepts unsolicited requests is not stated.
Assets
$2.1B
Grants
2,375
Total Given
$228.4M
Marin Community Foundation
Novato, CA
Marin Community Foundation funds work in affordable housing and homelessness, community resilience and power, as well as social services, education, arts and conservation, with a focus on marginalized Marin County residents and some broader U.S. and international grantmaking. Its 2025 grants had a median of $25,000, though amounts varied widely. The profile does not state whether it accepts unsolicited requests.
Assets
$1.3B
Grants
1,573
Total Given
$186.1M
Gates Foundation
Seattle, WA
The Gates Foundation funds work to reduce disease and poverty, improve health and gender equality in lower-income countries, and support education and economic mobility in the United States, especially Washington State; it works in more than 140 countries. Its 2024 grants had a median of $500,000, with awards ranging from $1 to $350.5 million. It generally does not accept unsolicited proposals, but periodically offers opportunities through published requests for proposals.
Assets
$78.7B
Grants
4,974
Total Given
$6.3B
More similar funders
More Funders in California
Cite this profile
Grantable. (2026). Tandem Philanthropies FKA the Ark Foundation funder profile. GrantGraph. Retrieved October 24, 2026, from https://grantable.co/funders/tandem-philanthropies-fka-the-ark-foundation-morg_91aff3b89e8845b58cc38c75a222e5dd
BibTeX
@misc{grantable_384055324_2026,
author = {{Grantable}},
title = {{Tandem Philanthropies FKA the Ark Foundation funder profile}},
howpublished = {GrantGraph},
year = {2026},
url = {https://grantable.co/funders/tandem-philanthropies-fka-the-ark-foundation-morg_91aff3b89e8845b58cc38c75a222e5dd},
note = {Accessed 2026-10-24. Data licensed CC BY 4.0}
}The figures on this page are open data under CC BY 4.0: reuse them with credit to Grantable and a link. Download the data.
Figures come from Tandem Philanthropies FKA the Ark Foundation's IRS filings (methodology). AI-written summaries, news items and logos are not covered by the open licence. Spot an error? Email hello@grantable.co.
Tandem Philanthropies FKA the Ark Foundation down — hundreds of funders to go?