Aaron Sosnick is the principal trustee of La Vida Feliz Foundation, and uses his foundation quietly to  support philanthropy in the arts, education, human services, and community projects.

"We recently stumbled on another wealthy individual associated with Caxton—Aaron M. Sosnick, who flies even more under the radar than Kovner, but is engaged a philanthropy at a significant level.

"Sosnick, who's in his late 40s, attended Wagner High School, where his father was a teacher. Wagner High, by the way, was on the now-defunct Clark Air Force Base in the Philippines. Sosnick graduated from the school in 1984 and attended MIT, graduating in 1988. Sosnick later joined Caxton Associates, and is at the helm A.R.T. Advisors, a statistical arbitrage fund that operates from Caxton's office. Sosnick has ties to both the East and West Coasts and his philanthropy is also bicoastal— largely focused on Los Angeles and New York City. 

"It's not exactly clear how much Sosnick is worth, but his foundation, La Vida Feliz Foundation ("The Happy Life" Foundation), held some $433 million in assets in a recent year and gave away more than $18 million. That number may well now be higher now, as the foundation has really grown since its inception in 2007. Much like the Kovner Foundation, La Vida Feliz doesn't have much of a web presence or a clear way to get in touch. In addition, Sosnick is the only trustee on the books."--Ade Adeniji, Inside Philanthropy