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Prediction market share prices directly represent implied probabilities. A YES share priced at $0.70 implies a 70% probability of the event occurring. This page explains how to interpret prices and convert between common odds formats.

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Price as Probability

The simplest way to think about prediction market prices:
Share PriceImplied Probability
$0.055%
$0.2020%
$0.5050%
$0.8080%
$0.9595%
If you think the true probability is higher than the price implies, buying is a positive expected value bet. If you think it’s lower, the other side offers value.

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Converting Between Formats

Decimal odds show your total return per $1 wagered (including your stake).Formula: Decimal Odds = 1 / Price
PriceDecimal OddsMeaning
$0.205.00Win 5x your stake
$0.502.00Win 2x your stake
$0.801.25Win 1.25x your stake
Example: Buy at 0.25,decimalodds=4.00.A0.25, decimal odds = 4.00. A 10 bet returns 40ifyouwin(40 if you win (30 profit + $10 stake).

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Quick Reference Table

ProbabilityPriceDecimalAmericanFractional
10%$0.1010.00+9009/1
20%$0.205.00+4004/1
25%$0.254.00+3003/1
33%$0.333.00+2002/1
50%$0.502.00+1001/1
67%$0.671.50-2001/2
75%$0.751.33-3001/3
80%$0.801.25-4001/4
90%$0.901.11-9001/9

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Practical Applications

If a YES share is priced at $0.30 (implying 30% probability) but you believe the true probability is 50%, the expected value is positive:
  • Expected payout: 50% × 1.00=1.00 = 0.50
  • Cost: $0.30
  • Expected profit: $0.20 per share (before fees)
This is a +67% expected return if your probability estimate is correct.
Traditional sportsbooks build in a “vig” (commission) by making both sides slightly unfavorable. In prediction markets, you see raw probabilities. A -110 sportsbook line (implying ~52.4%) might be available at $0.50 (50%) in a prediction market—instant edge.
Real markets have bid-ask spreads. If YES is 0.48bid/0.48 bid / 0.52 ask, the true market probability is somewhere in between. The spread represents the cost of immediate execution.

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Fees and Effective Odds

Remember that Vistadex charges a 0.5% fee on trades. This slightly affects your effective odds:
  • Buying at 0.50with0.50.50 with 0.5% fee → effective cost ~0.5025
  • Your breakeven probability increases slightly
  • For most trades, the fee impact is minimal but worth considering on tight margins