Prediction Markets vs. Options-Implied Probabilities: Evidence from Gold and Silver Futures

Abstract

Prediction markets such as Polymarket are increasingly cited as real-time probability estimates for financial outcomes, yet it remains unknown whether their prices are consistent with the risk-neutral probabilities implied by options markets pricing the same events. Using 2,671 daily observations across 24 Gold and Silver CME futures threshold contracts over a six-month period, this paper finds that Polymarket systematically overprices the upside relative to Black-76 implied probabilities by 8.9 percentage points for Gold and 5.3 percentage points for Silver, a finding robust to seven independent checks and consistent in direction with a contemporaneous independent study on Bitcoin threshold contracts. The divergence exhibits AR(1) half-lives under three days, narrows significantly as expiry approaches, and cannot be fully explained by transaction costs or the commodity risk premium. These results suggest systematic mispricing in prediction market binary threshold contracts, though the observed magnitudes should be interpreted as upper bounds on behavioural mispricing given the structural wedge between risk-neutral and real-world probability measures.