Marilyn H. Simons, Ph.D., is an American businesswoman and philanthropist, the billionaire Co-founder and President of the Simons Foundation, one of the world's largest philanthropic organizations focusing on science and mathematics research. Her colossal wealth is tied to the fortune built by her husband, James 'Jim' Simons (d. 2024), the legendary founder of Renaissance Technologies (RenTech).

Simons holds a Ph.D. in Economics from the State University of New York at Stony Brook. Her career is defined by her profound commitment to science philanthropy and advancing mathematics education globally. Her structural role is tied to managing the family's assets for philanthropic purposes.

• Simons Foundation (Co-founder & President): The core philanthropic vehicle (managing $10 billion+ in assets), dedicated to science and mathematics research (including the Flatiron Institute).
• Renaissance Technologies (Family Heir): The foundational source of her wealth, tied to the highly secretive, successful quantitative hedge fund (Medallion Fund).
• Academic Background: She holds a Ph.D. in Economics and served as a teacher early in her career.
• Philanthropic Apex: She and her late husband committed billions of dollars to funding basic scientific and mathematical research.

Dr. Marilyn Simons's strategic leadership involves guiding the allocation of massive capital to scientific and mathematical research. She and Jim Simons co-founded the Simons Foundation in 1994, recognizing the structural need for private, flexible funding for basic science research (which is often neglected by government grants). Their $10 billion+ commitment makes it one of the largest philanthropic organizations globally.

Her structural contribution is immense: pioneering a high-impact, data-driven model for science philanthropy and establishing the Flatiron Institute (a major in-house computational research center). Her wealth is secured by the colossal liquid gains from the Renaissance Technologies hedge fund, which is renowned for its mathematical, black-box trading.

Dr. Marilyn Simons's social impact is massive and structural, tied to the Simons Foundation's role in funding foundational breakthroughs in mathematics, physics, and life sciences (a major structural contribution to global scientific discovery). Her work with Math for America (MFA) and the Flatiron Institute promotes STEM education and computational research.

Her structural contribution is tied to her belief in data-driven decision-making and intellectual excellence as the best path to social and scientific progress.

Marilyn Simons maintains the professional, composed style of an academic executive. Her attire is consistently formal and high-quality, favoring tailored suits. Her aesthetic reflects stability and immense intellectual authority, typical of a leader in global science philanthropy.

Residing in East Setauket, New York, her luxury is the immense security and financial reward derived from her multi-billion dollar fortune. Her life is dedicated to science philanthropy, investment management, and academic governance.