# Heising-Simons Foundation

Heising-Simons Foundation is an Endowment / Foundation based in Los Altos, United States.

## Overview

- **Organization type:** Endowment / Foundation
- **Headquarters:** Los Altos, United States
- **Region:** North America
- **Address:** 400 Main Street Suite 200, Los Altos, California, United States
- **Founded:** 2007
- **Assets under management:** 833 (Altss estimate)
- **Website:** hsfoundation.org
- **LinkedIn:** https://www.linkedin.com/company/hsfoundation

## Regulatory record

- **Reports private funds:** No

## About

The Heising-Simons Foundation was established in 2007 by Elizabeth Simons and Mark Heising. Simons is the daughter of Renaissance Technologies founder James Simons. The foundation maintains its headquarters in Los Altos, California. Grantmaking covers climate and clean energy, science research, early childhood education, and human rights. The foundation makes direct grants and supports organizations including the Environmental Defense Fund and Human Rights Watch. It also backs journalism and technology-society initiatives. Geographic reach centers on the United States with additional international human rights work. Positions include limited partner commitments through Medley Partners to Resolute Ventures, EQT, TA Associates, Charterhouse Capital Partners, and Endless LLP. The foundation lists 810 million dollars in total assets per recent filings. Mark Heising founded Medley Partners Management LLC, which manages private market investments for the family network. Additional offices are not disclosed. The family maintains the Heising-Simons Action Fund as a separate advocacy vehicle. December 2024: Sponsored International Human Rights Day events in San Francisco. The foundation operates with a dedicated board that includes next-generation family members. Caitlin Heising serves as vice chair. This governance model keeps investment advice at Medley Partners while grant decisions remain inside the foundation structure.

## Sectors

- Climate and Clean Energy
- Science
- Early Childhood Education
- Human Rights

## People

- Elizabeth Simons — Chair of the Board
- Mark Heising — Founder
- Caitlin Heising — Vice Chair of the Board

## Questions

### Who runs investment decisions at Heising-Simons Foundation?

Mark Heising directs private market exposure through Medley Partners Management LLC. The foundation board approves grant allocations separately.

### Does Heising-Simons Foundation participate in fund commitments or only direct deals?

The foundation holds limited partner positions in multiple private equity and venture funds via Medley Partners. Direct holdings include Uptrust and ParentPowered.

### How is Heising-Simons Foundation related to Medley Partners?

Medley Partners Management LLC serves as the family's investment advisor and manages assets linked to the foundation and related Simons entities.

### What investment stages does Heising-Simons Foundation typically target?

Through Medley Partners the foundation accesses venture capital and private equity across growth and buyout stages.

### What is Heising-Simons Foundation's known posture on co-investments alongside external GPs?

The foundation commits to external funds managed by Resolute Ventures, EQT, TA Associates, Charterhouse and Endless through its advisor.

## Related profiles

- [Meijer](https://altss.com/profile/meijer)
- [Amaury](https://altss.com/profile/amaury)

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Last updated: 2026-06-03T20:00:00.000Z

Canonical page: https://altss.com/profile/heising-simons-foundation

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