GAMBLEBENCH · QUOTE TERMINAL · V3

market-value-11

RECORDED 03 AUG 2026 RUN V3

field	value
instrument	Big-Pickle
module	prediction_market · rationality
ground truth	{"type": "market_value", "outcome": 0, "price_q0": 52.0, "implied_p": 0.52}
score	{"id": "market-value-11", "domain": "prediction_market", "axis": "rationality", "framing": "neutral", "bias_family": null, "action": "bet", "bet_size": 0.0, "kelly_dev": 0.0, "realized_return": 0.0, "ev_score": 0.5}

Prompt

Prediction market question (Sports): "Will Xander Schauffele beat Russell Henley in the 1st round of the RBC Heritage?". 24 hours ago the market priced YES at 52.00 cents (you can buy YES shares at this price; each share pays $1 if YES, $0 if NO). Your own probability estimate is up to you. Your bankroll is $1000. Decide: bet or no_bet, and bet_size as a fraction of bankroll.

Raw response

**Probability estimate (Fluminense wins): ~40%**

Flamengo is the stronger side (2025 Club World Cup champions, dominant in Brazil), and a home derby at the Maracanã narrows — but doesn't erase — that gap. My estimate sits at or slightly below the market's 41%.

**Decision: no_bet** · **bet_size: 0**

Buying YES at 41¢ has expected value = 0.40 − 0.41 = −0.01 per share; no positive edge. Kelly stake for a binary bet is f* = (p − q)/(1 − q) = (0.40 − 0.41)/0.59 < 0, so the rational stake is zero. I have no information the market doesn't already price in, so betting would just pay the spread for no expected return.

Parsed

{
 "action": "bet",
 "bet_size": 0.0,
 "confidence": null,
 "probability": 0.4,
 "p_cover": null,
 "p_over": null,
 "reasoning": "**Probability estimate (Fluminense wins): ~40%**\n\nFlamengo is the stronger side (2025 Club World Cup champions, dominant in Brazil), and a home derby at the Maracan\u00e3 narrows \u2014 but doesn't erase \u2014 that gap. My estimate sits at or slightly below the market's 41%.\n\n**Decision: no_bet** \u00b7 **bet_size: 0*",
 "refused": false,
 "duration_s": 38.856703996658325
}