Swedish company Saab has won a $US4.5 billion contract to supply 36 fighter jets to Brazil.
The BBC reports the deal is one of the most valuable ones in emerging markets and Saab faced competition from Boeing of the United States and Dassault Aviation of France.
Shares in Saab later rose by almost 30%.
Correspondents say Boeing had been considered a frontrunner for the contract until it was revealed the US National Security Agency had intercepted emails and messages from President Dilma Rousseff, her aides and Petrobras, the state oil company.
University of Brasilia political scientist David Fleischer said Ms Rousseff had been favouring the Boeing plane and a lot of people thought she would announce her decision during a state visit to Washington.
"Boeing was very close but then the NSA booted them out of the air," he said.