The Same Bet, Two Different Prices. That Gap Is the Opportunity
Prediction markets are strange and fascinating things. Thousands of traders simultaneously price the probability of real-world events, from elections to Fed decisions to whether a specific bill passes Congress. The markets are efficient enough that they often outperform expert forecasts and polls. But they are not so efficient that every platform agrees.
When Polymarket says a candidate wins with 64% probability and another platform says 57%, someone is wrong, or at least one of them is more wrong. That 7-point gap is a signal; it might be an arb, it might be an edge, or it might reflect genuinely different information or participant bases. But you cannot find the gap if you are only looking at one market.
The FatNarwhal Prediction Market Comparator puts the same events side by side across platforms, normalizes the prices into comparable probability terms, and shows you the spread. No more switching between tabs to check where the consensus really sits.
How to Use It
Come to fatnarwhal.com and scroll to the live comparator.
The table shows active prediction markets grouped by topic; politics, economics, markets, sports, and others. For each event you can see the current probability on each platform side by side, the spread between the highest and lowest price across platforms, and a consensus probability aggregated from all available sources.
Click into any market to see the full detail; the price history on each platform, the volume and liquidity, and how the spread has changed over time. A spread that is widening usually means something is moving on one platform and not yet on others; that is when it is worth looking hard.
The consensus column is where to start every time. If the consensus is 60% but you see one platform at 65% and another at 55%, you have a 10-point spread to investigate. Is the 65% platform correct and the 55% one behind? Is the 55% one picking up on something the other missed? Or is it just a liquidity difference and both will converge?
How the Math Works
Converting any market price to an implied probability is straightforward; prediction market shares trade between 0 and 1 (or 0¢ and 100¢), where the price is the market's estimate of the probability that event resolves Yes.
A share trading at $0.62 implies a 62% probability. A No share on the same market trading at $0.41 implies a 41% probability of No, which means the market is embedding about a 3-point vig (62% + 41% = 103% instead of 100%).
The comparator normalizes all prices across platforms into probability terms and then strips the implied vig using the de-vig methodology so all numbers are on a fair, comparable basis. When you see the spread, it is a clean probability difference, not a number contaminated by different platform margins.
The consensus is a weighted average of fair probabilities across platforms, with weights adjusted for liquidity; higher-volume markets get slightly more weight on the assumption that more money has gone into price discovery.
When to Use It and When Not To
Use it before placing any prediction market position. Checking the comparator first takes thirty seconds and ensures you are always getting the best available price. Use it to track how quickly different platforms respond to breaking news; some markets are faster than others, and knowing which ones tend to lead can itself be an edge.
One thing the comparator will not tell you is which platform is right. It shows you the disagreement; figuring out why requires your own research and judgment. High spreads are a starting point for investigation, not a trade signal by themselves.
Also worth knowing; the comparator reflects market prices, not fundamental probabilities. If all platforms are slow to update on a major news event, the consensus will also be slow. The tool is most useful in combination with your own analysis, not as a replacement for it.
Try It
Come to fatnarwhal.com and look at whatever is the biggest political or economic event active right now. Find the highest spread in the comparator. Ask yourself why two platforms are pricing it so differently. That question is where the interesting trading opportunities live.
One event. Multiple markets. One place to see all of them.