# Marianthi Foundation

Marianthi Foundation is an Endowment / Foundation based in New York, United States.

## Overview

- **Organization type:** Endowment / Foundation
- **Headquarters:** New York, United States
- **Region:** North America
- **Address:** New York, NY, United States
- **Founded:** 1994
- **Assets under management:** ~$87M (Altss estimate)

## Regulatory record

- **Reports private funds:** No

## About

The Marianthi Foundation was established in 1994 by P. Roy Vagelos and his wife Diana, formalizing a family philanthropic tradition anchored by the wealth Roy Vagelos generated as CEO of Merck and later as Chairman of Regeneron Pharmaceuticals. Named after Roy Vagelos's mother, the foundation directs capital primarily toward university-level educational projects, biomedical research, and environmental causes, reflecting the family's scientific and academic values. While grantmaking defines its public identity, the foundation maintains an active investment posture concentrated in buyout strategies across multiple asset classes. A substantial portion of the foundation's balance sheet derives from P. Roy Vagelos's long-standing relationship with Regeneron, where he has served as Chairman and accumulated significant equity. The foundation is governed by a tight family board. Diana T. Vagelos serves as Vice President and Treasurer while also holding a trustee role at Barnard College. The next generation is represented through directors Andrew Vagelos and Cynthia Vagelos Roberts. P. Roy Vagelos's professional affiliations — including membership in the National Academy of Sciences and the American Academy of Arts and Sciences — extend the foundation's reach into elite scientific and institutional networks that can inform both grantmaking and investment sourcing. The structural differentiator is the fusion of a scientist-CEO's investment judgment with a grantmaking mission. Unlike many foundations that outsource investment decisions entirely to an OCIO, the Marianthi Foundation appears to blend direct buyout exposure, real assets, and private credit alongside concentrated public-company equity from Roy Vagelos's board-level corporate relationships. This hybrid posture — part family office, part institutional foundation — is unusual for a vehicle of its reported scale, and it ties the foundation's financial durability directly to Roy Vagelos's presence and Regeneron's trajectory.

## Sectors

- Pharmaceuticals & Biotech
- Real Estate
- Private Credit

## People

- P. Roy Vagelos — Founder
- Diana T. Vagelos — Vice President and Treasurer
- Andrew Vagelos — Director
- Cynthia Vagelos Roberts — Director

## Questions

### How is the Marianthi Foundation related to Regeneron Pharmaceuticals?

P. Roy Vagelos serves as Chairman of Regeneron, and the foundation holds significant Regeneron equity — making the biotech company's stock performance a material factor in the foundation's investment portfolio. This creates an unusually concentrated link between a single public company and a grantmaking foundation's balance sheet.

## Related profiles

- [Lincoln Center Pension Plan](https://altss.com/profile/lincoln-center-pension-plan)
- [Mike & Gillian Goodrich Foundation](https://altss.com/profile/mike-gillian-goodrich-foundation)

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Last updated: 2026-08-11T02:43:31.692Z

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