Brazil's election: Predicting the market outperforms polls in the first round of voting

First round results of Brazil's election: Bolsonaro leads Lula, predicting the divergence between the market and polls is controversial.

In the first round of voting in the Brazilian presidential election, Flavio Bolsonaro surpassed current President Lula's 45.16%, with 47.03% of the vote, and neither party obtained an absolute majority. This result led to the election entering a second round of voting scheduled for October 25. Although mainstream polls show Lula in the lead, forecast market platforms have shown Senator Bolsonaro in the lead since September. The contrast has once again sparked debate about the reliability of prediction markets, even though such platforms have been banned in Brazil.

Quick overview of key points

First-round results: Flavio Bossonaro (47.03%) leads Lula (45.16%), and the second round of voting will be held on October 25.

Market volatility: On the Polymarket platform, Bolsonaro's winning percentage rose from about 22% in July to more than 80% after the poll was released.

Legal background: Brazil has banned participation in election-related gambling activities since the relevant regulations came into effect in May.

First-round results deviate from poll trends

Previously, the already controversial forecast market in the UK, closely follows Brazil's campaign. However, voting results released on Sunday showed significant gaps with the data from major polling agencies.

Current Senator Flavio Bosonaro, son of former President Jair Bosonaro, received 47.03% of the vote, while Lula received 45.16%. Since no candidate has won an absolute majority, the election will enter the second round of decision-making on October 25.

In contrast, data from well-known polling agency Datafolha shows that Lula leads with 42% approval rating, while Bolsonaro has 38%. Other polls also predict a close election.

After the results were announced, Lula admitted that he had thought he would win outright in the first round and called on supporters to continue the campaign. "I am sure I will win the first round of the election. Bolsonaro represents national uncertainty."

Market odds reversed as early as September.

Since its launch in September 2025, the Polymarket contract focused on Brazil's elections has had cumulative transaction volume exceeding US$171 million.

At the beginning of July, based on platform odds, Flavio Bossonaro had a winning probability of about 22%, while Lula had 60%. But starting in September, the trend reversed. On September 20, Bolsonaro's winning percentage rose to about 58%, while Lula dropped to 42%. The Kalshi platform also shows a similar trend.

According to data collected on Monday, after the first round of voting, Bossonaro's victory percentage climbed to about 82%, compared with Lula's 17.5%.

The 2024 U.S. election has attracted attention to the gap between polls and forecast markets. In this mid-term election, both approaches tend to coincide, pointing to a Democratic victory.

Lack of Brazilian voter participation 'market'

This comparison requires important supplementary clarifications. According to Brazilian National Monetary Council Resolution 5,298 (effective May 4), derivatives trading related to political, electoral, sporting or cultural events is strictly prohibited.

Subsequently, Brazil's Ministry of Finance ordered the blocking of 27 platforms, including Polymarket. In July, the platform restricted Brazilian accounts from closing positions and not opening new positions. In other words, the participants influencing these markets are not typical of Brazilian voters.

This phenomenon is not limited to Brazil. In France, Polymarket was blocked ahead of the 2027 presidential election, and the event had previously been closely watched on the platform. Elon Musk's response on the X platform in late September also helped draw public attention to these markets.

Therefore, the second round of voting on October 25 will further reveal the gap between polls and forecast markets. However, when analyzing the results, the specificity of the audience must be taken into account. In addition, their role in democratic decision-making continues to spark widespread debate.