Nat, along with his wife Laura, co-founded Sea Change Foundation, a private family foundation currently dedicated to addressing global climate change. Founded in 2006, Sea Change works to support private and public policies and foster investments and practices that will reduce the most substantial sources of greenhouse gas emissions. In 2009, Nat started Prelude Ventures, an early-stage cleantech investment group which focuses on emerging companies poised to speed the transition to a low-carbon economy. Prelude works closely with other venture funds and family offices active in cleantech. Prelude manages capital exclusively for Simons family philanthropic entities and is a member of the Breakthrough Energy Coalition. Nat founded and oversees Meritage Group LP, a U.S.-based investment management firm with exposure to many asset classes and strategies. Meritage spun out of Renaissance Technologies, where Nat was a principal. Nat remains a board member of Renaissance. Nat holds a B.A. in Economics and an M.A. in Mathematics from U.C. Berkeley. He is a member of the U.C. Berkeley Board of Visitors. In 2017, he and his wife Laura signed the Giving Pledge.