Polymarket sometimes lets YES and NO trade for less than $1.00 together. Buy both, the market pays you $1.00 at resolution - minus fees and slippage. Technically: this is sum-to-one arbitrage, executed against the CLOB matching engine with sub-500ms latency. We size positions against orderbook depth so you don't move the price against yourself.
Same machinery, different signals. Pick the one that matches your capital and risk profile.
YES + NO < $1.00 on the same market. When the orderbook sells YES at 49¢ and NO at 49¢, buy both - guaranteed $1.00 payout at resolution. Edge: typically 1-3¢ per dollar, holding period: days to weeks.
Same outcome priced differently across two Polymarket markets. Less common but higher edge when it appears. Requires market-mapping logic to spot.
Polymarket vs Kalshi on the same event. Two regulated venues, two prices, one truth. See the dedicated page →
Configurable thresholds. Auditable runs. If a trade fires, the matching log line is in the dashboard.
# Sum-to-one arbitrage scanner - example client config strategy: "sum-to-one" markets: categories: ["politics", "crypto", "economics"] min_volume_usdc_24h: 25_000 # skip illiquid books min_days_to_resolution: 1 trigger: min_edge_cents: 1.5 # YES.ask + NO.ask <= 0.985 min_orderbook_depth_usdc: 500 # both legs combined execution: legs_in_parallel: true # YES and NO fire simultaneously slippage_bps: 50 partial_fill_policy: "unwind" # if only one leg fills, exit risk: max_position_usdc: 5_000 max_concurrent: 15 daily_drawdown_stop_usdc: 800
The 2¢ floor of 2024 was 1¢ in late 2025. We size strategies for what's actually available today, not what was profitable two years ago.
If your YES leg fills at 49¢ but NO bounces to 53¢ before your second leg lands, you're long YES with no hedge. Our default policy unwinds the partial fill - but that costs ~30bps. Bake it into the math.
Polymarket resolution disputes are rare but they happen. A 2¢ edge held for 3 weeks pays roughly the same as a 1-day USDC yield. If you're not getting paid for the time risk, don't trade.
Polygon gas is cheap (~$0.005/trade) but you still pay it on both legs. Below ~$200 position size, gas eats your edge. We enforce minimum sizes in code.
Generalizations, not promises. Edges rotate.
Long-tail elections (parliamentary, governorships). Liquidity asymmetry between YES/NO sides creates floors.
Fast-resolving binary markets on BTC price thresholds. Tighter but more frequent.
Niche outcomes with thin books. Watch fees - Polymarket's 2% on certain sports markets eats arbs.
Sum-to-one scanner with risk caps. Good first arb bot.
Multiple strategies running in parallel, including cross-platform Polymarket↔Kalshi.
Send us your capital range and target edge. We'll come back with a strategy spec, backtest results from public data, and a quote.