Described as "the most influential Mexican on Wall Street," Martínez played a major role in the restructuring of Argentina's sovereign debt and described himself in 2013 as having participated in nearly every restructuring of sovereign debt during the previous 25 years. His investments have been characterized as extending "from New York to Patagonia." He is a major holder of assets in Argentina, with Fintech Media LLC, a subsidiary of Fintech Advisory, owning "more than a billion dollars in financial assets" in Argentina alone.