Flávio Bolsonaro holds an 87% implied probability in the runoff market after leading the October 4 first round with 47% of valid votes to incumbent Luiz Inácio Lula da Silva’s 45%, advancing both to the October 25 contest. Multiple post-first-round surveys, including Ipespe, AtlasIntel, Datafolha, and PoderData, show the Liberal Party senator ahead by 4–6 points on valid votes, driven by consolidation of right-leaning support, stronger perceived performance on crime, the economy, and fiscal issues, and voter dissatisfaction with Lula’s 43% approval rating amid 53% negative economic assessments. Historical patterns in Brazil, where first-round leaders have prevailed in runoffs since the return to democracy, further shape trader consensus reflected in the pricing.