25. Keith Campbell Foundation for the Environment

KEITH CAMPBELL, 45
Campbell & Co. (hedge fund)
Giving: $5.1 million
Assets: $121.8 million
Campbell concentrates almost exclusively on environmental causes in and around Maryland, including several Chesapeake Bay Foundations ($2.2 million).

26. Samberg Foundations
ARTHUR SAMBERG, 66
Pequot Capital (hedge fund)
Giving: $5 million
Assets: $82.9 million
Samberg contributes to the Harlem Children's Zone ($1 million), which focuses on improving the quality of life for disadvantaged children and their families in New York City, and several Jewish causes, including the U.J.A.-Federation ($700,000).

27. Dalio Family Foundation
RAY DALIO, 58
Bridgewater Associates (hedge fund)
Giving: $4.9 million
Assets: $20.4 million
Dalio gives to a wide range of recipients, from the Robin Hood Foundation ($1.1 million) to Ducks Unlimited ($250,000), a nonprofit dedicated to preserving wetlands and waterfowl.
Bonus fact: The foundation donates to Maharishi University of Management ($1 million), which teaches meditation to inner-city kids.

28. Johnson Family Foundations
CHARLES AND RUPERT JOHNSON, 74 and 65
Franklin Resources (mutual fund)
Giving: $4.6 million
Assets: $208.3 million
There's a West Coast bent to the Johnsons' largesse, from the California Academy of Sciences ($1.2 million) to the Fine Arts Museums of San Francisco ($50,000).
Bonus fact: This is the "other" Johnson mutual-fund family (not the one from Fidelity).

29. Barakett Foundations
TIMOTHY AND BRETT BARAKETT, both 41
Atticus Capital, Tremblant Capital (hedge funds)
Giving: $4.6 million
Assets: $2.8 million
Timothy donated $1 million to the Robin Hood Foundation, and Brett gave $10,000 to the New York Heart Association.

30. Jacobson Family Trust Foundation
JONATHAN JACOBSON, 44
Highfields Capital (hedge fund)
Giving: $4.4 million
Assets: $76.2 million
Jacobson's giving concentrates on Massachusetts charities like the Combined Jewish Philanthropies ($1.2 million), in Boston.