The Ibovespa fell more than 0.5% to trade below the 173,000 mark on Monday as investors awaited a public hearing in Washington on the US trade investigation into Brazil for the possibility of additional tariffs on Brazilian products.
The hearing will consider imposing a 25% tariff on Brazilian goods following an investigation into the country's trade practices.
The USTR said it had identified what it described as "unreasonable" practices.
Shares of major exporters declined, with Vale down 0.7%, Petrobras losing 1%, and Minerva slipping 0.6%.
Petrobras was also pressured by lower oil prices after OPEC+ agreed to raise its production target starting in August and shipping through the Strait of Hormuz continued to normalize.
Other notable decliners included Bradesco (-2.6%), Ambev (-2.6%), WEG (-1.0%), and Rede D'Or (-1.6%).