Brazil presidential election

What exactly resolves?

Polymarket uses credible reporting, with TSE official results for ambiguity. Kalshi’s full contract is the governing source for its winner definition. A poll showing a lead is neither the result nor a certainty of victory.

Polymarket lists October 4 as its API end date, yet the text includes a potential runoff and a June 30, 2027 long-stop. Kalshi lists a 2027 close. Do not use either API timestamp alone as the forecast deadline or settlement duration.

Are the two platforms asking the same question?

Both selected titles refer to the eventual election winner, not the first-round leader. Polymarket explicitly includes a second round and a June 2027 fallback to Other. Kalshi’s API supplies a short winner condition and a later close timestamp; the complete contract must establish any exception equivalence. Equivalence is not proven by the titles.

Is there room at the quoted price?

Depth below is measured from the captured book within 2¢ of each side’s best ask. The 100- and 1,000-share examples consume successive ask levels. These are snapshots of visible entry liquidity, not reservations, total market capacity, or exit guarantees. Kalshi asks are derived as 1 minus the opposing bid with its available quantity.

Reported 24h activity: Polymarket parent event 1,053,583 USD; selected contract 291,104 USD. Kalshi parent event 105,870 contracts; selected contract 15,447 contracts. These units are not interchangeable.

Both sides: upside is not the same as likelihood

One hypothetical share at each captured ask, before fees. The price is not a measured win probability. A winning share pays one unit; a losing share pays zero. Football ties and exceptional settlement can pay other amounts.

Return if win is conditional net gain ÷ entry cost. It is not expected return, annualized return, or a recommendation. Fees lower the gain and increase the amount at risk.

Evidence and forecasting thesis

A market-derived benchmark avoids inventing a polling model. Changing the assumed probability demonstrates how much independent evidence would be needed to overcome the ask and fees.

• Representative polls, field dates, methodology, and correlated polling error; no poll aggregation was fitted in this study.
• Runoff matchups, turnout, and vote transfers. Leading a first round does not necessarily predict the final winner.
• Candidate eligibility and official rulings. Distinguish confirmed decisions from commentary.

What would invalidate the assessment: A candidate-status change or official result requires revisiting the model. A forecast based on first-round polling alone does not justify a final-winner probability.

Risk profile: Political surprise, correlated polling misses, runoff changes, delayed certification, and resolution ambiguity. Long holding periods add opportunity cost even if the outcome is ultimately favorable.

Probability model and payoff sensitivity

The starting benchmark is the captured Polymarket bid–ask midpoint, 60.65%. No validated independent model justifies changing it. Lower and higher scenarios move this assumption by five percentage points; they are not confidence bounds or recommendations. Figures use 100 shares at the best ask plus an illustrative 1¢ per share total fee allowance. Larger entries require the depth simulation.

Formula: expected net = N × [p(win) + 0.5 × p(tie) − entry − fee]. The binary table assumes p(tie)=0. Break-even under that assumption is 61.70%. A better-looking result after increasing p proves only that the calculation responds to p.

Every tool’s contribution

Observed inputs, calculated outputs, actual provider responses, and tools that cannot support this study are identified separately. All sixteen learning tools are accounted for.

Actual provider outputs: inspect before trusting

Jev returned different for the rule comparison, with classification confidence 86.00% using jev-1.13.0. This is not the event’s probability. The request rubric and full distribution are in the evidence download.

Drift forecast window: 2026-09-21T23:41:59.839002Z to 2026-10-04T00:41:59.839002Z. Quality flag: low_data. Rejected for probability modeling. Near-zero variation in a projected band is not proof of low risk.

EWZ.US is a Brazil-equity proxy. It also responds to currency, commodities, and global equities, so its movement is not a candidate-win probability or election-result source.

EODHD returned 20 daily records for EWZ.US. Latest record: 2026-09-21, close 38.0700 in quoted instrument units. Retrieval: 2026-09-21T22:41:42.201Z. Same-day values may not be final. No election, policy, or touch-threshold probability was derived from them.

No dated news was returned for the last seven days. This does not establish that no news exists.

{
  "research": {
    "status": 200,
    "body": {
      "topic": "Will Flávio Bolsonaro win the 2026 Brazilian presidential election?",
      "keywords": [
        {
          "term": "Flávio Bolsonaro",
          "score": 95,
          "trend": "rising"
        },
        {
          "term": "Lula",
          "score": 90,
          "trend": "rising"
        },
        {
          "term": "Brazilian presidential electio",
          "score": 88,
          "trend": "rising"
        },
        {
          "term": "Polls",
          "score": 80,
          "trend": "rising"
        },
        {
          "term": "Supreme Court scandal",
          "score": 75,
          "trend": "rising"
        },
        {
          "term": "Jair Bolsonaro",
          "score": 70,
          "trend": "stable"
        },
        {
          "term": "Corruption",
          "score": 65,
          "trend": "rising"
        },
        {
          "term": "Public security",
          "score": 60,
          "trend": "stable"
        }
      ],
      "coverageIndex": 90,
      "coverageTrend": "accelerating",
      "coverageChangePct": 45,
      "sentimentScore": 15,
      "sentimentTrend": "improving",
      "signalScore": 70,
      "signalDirection": "bullish",
      "interpretation": "Flávio Bolsonaro is currently in a statistically tied race with incumbent President Lula for the 2026 Brazilian presidential election, with some polls showing him slightly ahead in a potential runoff. A recent Supreme Court scandal involving a banker accused of financial fraud has energized Bolsonaro's right-wing base and shifted public attention, despite his own alleged ties to the same banker. Bolsonaro is campaigning on a hardline public security platform and aiming to present a more moderate image than his father, Jair Bolsonaro.",
      "leadingIndicators": [
        "Flávio Bolsonaro is polling neck-and-neck with Lula in recent surveys.",
        "A Supreme Court scandal has energized Bolsonaro's base.",
        "Bolsonaro is actively campaigning on public security and economic platforms."
      ],
      "watchNext": [
        "First round of the Brazilian presidential election on October 4, 2026.",
        "Potential second round runoff election on October 25, 2026.",
        "Further developments in the Supreme Court financial scandal and any new corruption allegations."
      ],
      "confidence": "High",
      "dataWindow": "7 days"
    }
  },
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    "status": 429,
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      "requestId": "8e4b2637-a79d-470b-b856-877b57117304"
    }
  }
}

Costs, participation mechanics, and limits

• Entering: choosing a side, size, and price is different from receiving a fill. A limit can remain unfilled; crossing available quotes can consume multiple levels. These pages place no orders.
• Exiting: today’s entry depth says nothing certain about future bids. Early exit introduces a future-price assumption and may add fees. A marked gain is not a realized payout.
• Fees: all five captured Polymarket markets report fees enabled; the legacy fee endpoint returns base_fee 1000. This study does not interpret that as a flat 10% charge. Use the current market-specific schedule and rounding. Kalshi’s series fee type is quadratic; overrides and execution type can matter.
• Time and settlement: distinguish the event time, order close, resolution, dispute period, and withdrawal availability. Holding time and currency/funding costs are excluded from the scenario.
• Eligibility and access: platform and regional rules apply. Educational access to these pages does not establish eligibility to transact on either venue.
• Concentration: related topics may move together. The five studies are a learning set, not a diversified portfolio or an allocation proposal.

Polymarket fee documentation · Kalshi fee schedule