Recent Brazilian presidential first-round turnout has clustered tightly around 79% of registered voters in the past three cycles, reflecting compulsory voting rules offset by consistent abstention near 20%. With the October 4 vote days away and polls showing Lula holding a narrow first-round edge over Flavio Bolsonaro while the runoff remains statistically tied, trader pricing centers on 78-80% as the modal outcome. Close competition and standard mobilization by major parties and regional machines support participation levels in line with recent baselines, while analyses noting higher potential abstention among Lula-leaning voters introduce modest downside risk without evidence of broader shifts from economic conditions, weather, or logistical changes.