Academic lifeParnes graduated in economics in the early 1980s at the , where he was a colleague of (Central Bank of Brazil, BC's president between 1999 and 2002). From 1986 to 1987, he got his master's degree in economics from the same institution, and then went with his family to the United States, where he earned a doctorate at the University of Pennsylvania, specializing in macroeconomics and international finances.
CareerUpon returning to Brazil in 1991, Parnes went working to the BBM Bank of Rio de Janeiro. From 1994 to 1995 he was employee of the Matrix Bank, but then returned to BBM. On November 27, 2001, he was invited by Armínio Fraga to become Director for International Affairs of the (a position that Fraga himself had held between 1991 and 1992), replacing Daniel Gleizer. Parnes was sworn in January 2002 and remained in office during the transition (2002–2003) of the Fernando Henrique Cardoso government to the Luís Inácio Lula da Silva. On September 10, 2003, citing personal reasons, Parnes sent his resignation to the Ministry of Finance (Brazil), Finance Minister, Antonio Palocci. The economist Alexandre Schwartsman was appointed for the position. In 2004, Parnes returned to the Banco BBM, where he remains to date. In 2007, he was elected "Best Specialist Manager of the Year" and "Best Specialist Manager of Leverage (finance), Leveraged Funds", by the ''Exame (magazine), Exame'' magazine.