The same event — like “Will Bitcoin exceed $100k by March 2026?” — can be listed on multiple prediction market platforms. Each platform has its own traders, order book, and pricing. Sometimes, the combined cost of buying opposite outcomes across two platforms is less than the guaranteed payout. That difference is locked-in profit — this is cross-platform arbitrage.

How It Works

Imagine YES on one platform costs $0.63 and NO on another costs $0.34. You pay $0.97 total for positions that pay $1 no matter the outcome. That’s a small, risk-free spread. You’re not betting on direction — you’re exploiting pricing discrepancies between independent markets.

Why Prices Diverge

• Different Users: Platforms attract different trader communities. One reacts faster or interprets news differently, creating temporary price gaps.
• Cross-Chain Friction: Platforms may run on different blockchains. Moving capital between them takes time and fees, slowing convergence.
• Limited Arbitrage Activity: Few traders actively run cross-platform arbitrage, so inefficiencies last longer than in traditional finance.
• Emotional Trading: Participants often react to headlines or tweets, temporarily pushing one platform out of line with another.

Conditions for Successful Arbitrage

Every condition must be satisfied to avoid turning a “risk-free” trade into a loss:

1. 
   Resolution Rules Must Match: Both platforms must define the event identically, using the same data source and edge case handling. Even slight differences can destroy the arb.
2. Timing Must Align: Markets must cover the same exact window. Slight differences in expiry or grace periods can invalidate the trade.
3. Platform Trust: Your capital is locked on both platforms. If either platform freezes withdrawals or disputes a resolution, your risk-free position becomes risky.
4. Liquidity: There must be enough depth to execute your desired position without moving the market. Small spreads are useless if you can’t fill enough shares.
5. Capital Lock-Up: Your funds are tied until the event resolves. Short-term spreads are far more valuable per unit of capital than long-term ones.
6. Fees: Consider trading fees, blockchain gas fees, and cross-chain bridge costs. Maker orders often save fees; taker orders can erase profits.
7. Execution Risk: Both legs must be executed almost simultaneously. Pre-deposit funds on both platforms, use limit orders, and accept that some opportunities will slip away.

Platform Comparisons

• Polymarket ↔ Opinion Trade: Best overall. Low fees, overlapping markets, established bridges. Main challenge: bridging time.
• Polymarket ↔ Kalshi: Deep liquidity but slower capital movement due to fiat/crypto split. Resolution sources may differ.
• Polymarket ↔ Probable: Promising if liquidity grows. Crypto-native, zero fees possible.
• Polymarket ↔ Limitless: Useful for longer-term markets; fees can rise near resolution.
• Opinion Trade ↔ Probable: Same chain, fast execution, low fees, but liquidity limited.
• Any platform ↔ unproven platforms: Avoid — counterparty risk is too high.

Realistic Profitability

• Major markets: spreads under 1%, usually not enough for meaningful returns.
• Mid-tier and niche markets: spreads 1-5%, often during fast-moving news.
• After fees: maker execution on Opinion Trade is critical. Taker orders near 50% probability can wipe out profits.
• Conservative annual return: 25–60% on actively deployed capital, depending on activity, pre-positioning, and fee management.

Arbitrage isn’t passive. Capital is locked, execution requires attention, and opportunities are limited by liquidity.

Tools to Make It Work

• Arbitrage Scanners: OplyScan, ArbBets, Oddpool Arb Dashboard
• Market Analytics: PolymarketScan, Polytrage
• Bridges: Stargate Finance, Jumper Exchange
• Platform Selection: Stick to well-established platforms with clear resolution rules and liquidity.

The Bottom Line

Cross-platform arbitrage works because most traders don’t compare prices, and infrastructure is still manual. The edge persists longer than in traditional finance.

It requires:

• Verification of resolution rules
• Pre-positioned capital on multiple chains
• Daily monitoring
• Fee awareness and careful order placement
• Patience and discipline

It’s not flashy or passive. It’s operational work, but for those willing to do it, it’s one of the more reliable edges in prediction markets today.