Recent first-round turnout of 78.92% on October 4 has anchored trader expectations for the October 25 runoff between incumbent Luiz Inácio Lula da Silva and Flávio Bolsonaro. Brazil’s electorate of 158.7 million is older than in prior cycles, with voting optional after age 70, reinforcing a multi-year pattern of gradually rising abstention that produced the highest rate since 1998. Polarization between the two leading candidates, both carrying substantial rejection levels, typically sustains mobilization among core supporters and limits further drops in participation. The 78–80% outcome leads market pricing because it aligns closely with observed first-round results and historical runoff benchmarks near 79%, while scheduled campaign events through late October offer limited scope for sharp shifts absent major surprises.