Weld is a member of the Council on Foreign Relations. He co-chaired its Independent Task Force on North America, which studied the liberalization of markets and free trade between the US, Canada, and Mexico. He was a principal at Leeds, Weld & Co., which describes itself as the United States's largest private equity fund focused on investing in the education and training industry. Weld serves on the board of directors of Acreage Holdings. For a time, he wrote thrillers and works of historical fiction.