Traders make Flávio Bolsonaro a heavy favourite for Brazil's runoff

Two venues price him near 88% to beat Lula on 25 October, up 24 points in seven days.

In one line: Flávio Bolsonaro wins Brazil's 25 October runoff over Lula, but narrowly; an 88% price overstates his chances, and a Lula win in the count proves this wrong.

Traders on Polymarket now give Flávio Bolsonaro an 88% chance of winning Brazil's presidency, up 24 points over the 7 days from 64% on 4 Oct, the day of the first round. The contract hit its 7-day high of 89% on 9 Oct and has slipped 0.7 points in the last 24 hours. It stood at 84% when the last digest ran on 8 Oct.

Kalshi prices the same question at 87%, and both venues put Lula at 12%. Two separate books agreeing within a point makes the price harder to dismiss. The rest of the Kalshi field is empty: Augusto Cury at 1%, Jair and Eduardo Bolsonaro at 0%. The race is Flávio against Lula.

The listed resolution date of 5 Oct has passed, but the rule says the market "includes any potential second round" and resolves on "a consensus of credible reporting". The part not yet met is a winner. The runoff falls on 25 October, and the rule allows until 30 June 2027 before an unknown result pays "Other".

The price has run ahead of the evidence. Flávio's first-round lead, which the last digest saw lifting his odds, is the fact behind it. A runoff is a new contest, in which voters for eliminated candidates choose again and Lula's camp has until polling day to close the gap. Since 8 Oct traders have added 4 points without a vote cast.

Flávio Bolsonaro wins the 25 October runoff, but by a narrower margin than an 88% price implies, which overrates him. The other side's best case is that the 26-point climb from the 4 Oct low reflects a first-round gap too wide for Lula to close; a clear Flávio lead in the official count would bear that out. The call is wrong if the official count on 25 October gives Lula the presidency, an outcome both venues rate at 12%. The result decides whether Brazil keeps Lula or hands the presidency back to the Bolsonaro family.