How NegRisk multi-outcome markets work on Polymarket: sum-to-1 mechanics, the negRisk flag in CLOB orders, why YES legs across NegRisk are not interchangeable, and execution best practices.
How NegRisk multi-outcome markets work on Polymarket: sum-to-1 mechanics, the negRisk flag in CLOB orders, why YES legs across NegRisk are not interchangeable, and execution best practices.
By Harley Young, lead writer at Polymarkets.co.il. Last reviewed: May 2026.
What this chapter covers
This is chapter 11 of our 32-part series on building a Polymarket trading bot. We cover the topic in depth across the sections below. Body content for each section is being written and rolled out chapter-by-chapter; FAQ answers and references are already complete and reflect production experience from running our own trader.
What NegRisk means (mutually exclusive Yes legs]
Why YES totals stay near 1 USD
The neg_risk parameter in order placement
Hedging across NegRisk legs
When NegRisk arb works (and when it does not)
Resolution edge cases
Code: place a NegRisk order
What NegRisk means (mutually exclusive Yes legs]
This section is in active development. Want to be notified when it goes live? Contact us or watch the authors page.
Why YES totals stay near 1 USD
This section is in active development. Want to be notified when it goes live? Contact us or watch the authors page.
The neg_risk parameter in order placement
This section is in active development. Want to be notified when it goes live? Contact us or watch the authors page.
Hedging across NegRisk legs
This section is in active development. Want to be notified when it goes live? Contact us or watch the authors page.
When NegRisk arb works (and when it does not)
This section is in active development. Want to be notified when it goes live? Contact us or watch the authors page.
Resolution edge cases
This section is in active development. Want to be notified when it goes live? Contact us or watch the authors page.
Code: place a NegRisk order
This section is in active development. Want to be notified when it goes live? Contact us or watch the authors page.
Frequently asked questions
What is a NegRisk market on Polymarket?
A multi-outcome market where the YES legs are mutually exclusive (only one can resolve YES). The sum of all YES prices stays near 1 USD because exactly one outcome wins. Examples: "2026 NBA Champion" (one team wins), "Next Fed chair" (one person).
Do I need to set a flag in the order to trade NegRisk?
Yes. Order requests for NegRisk markets must include neg_risk: true (Python: pass to OrderArgs; Node: pass in CreateOrderOptions). Forgetting the flag results in a rejected order or, worse, an order placed on the wrong order book. We hit this exact bug in production - commit 06deaef in our trader history.
Can I arbitrage NegRisk legs that sum to less than 1?
Yes - if all YES legs sum to less than 1.00 net of fees, buying every leg locks in a guaranteed profit. The arbitrage is real but extremely rare and gets sniped within seconds by faster bots. Treat it as a curiosity, not a strategy.
How is a NegRisk market resolved?
Same UMA optimistic oracle process as any other Polymarket market. The winning leg pays 1 USD per share, all losing legs pay 0. Resolution typically settles the entire NegRisk event at once.
Are NegRisk fees different from binary markets?
Same fee schedule as binary - 0% maker, 0.75-1.80% taker by category. The maker rebate also applies. The only practical difference is that you have N order books to manage instead of 1.
Can I hedge a YES position by buying the other NegRisk legs?
Yes - this is the NegRisk-specific hedge. If you are long one leg and want to lock in current PnL, buy the other legs in proportion. Net cost should be (1 - your YES leg price), modulo fees. We dont recommend it as a primary strategy because the fees usually eat the hedge edge.
Cau hoi thuong gap
What is a NegRisk market on Polymarket?
A multi-outcome market where the YES legs are mutually exclusive (only one can resolve YES). The sum of all YES prices stays near 1 USD because exactly one outcome wins. Examples: "2026 NBA Champion" (one team wins), "Next Fed chair" (one person).
Do I need to set a flag in the order to trade NegRisk?
Yes. Order requests for NegRisk markets must include neg_risk: true (Python: pass to OrderArgs; Node: pass in CreateOrderOptions). Forgetting the flag results in a rejected order or, worse, an order placed on the wrong order book. We hit this exact bug in production - commit 06deaef in our trader history.
Can I arbitrage NegRisk legs that sum to less than 1?
Yes - if all YES legs sum to less than 1.00 net of fees, buying every leg locks in a guaranteed profit. The arbitrage is real but extremely rare and gets sniped within seconds by faster bots. Treat it as a curiosity, not a strategy.
How is a NegRisk market resolved?
Same UMA optimistic oracle process as any other Polymarket market. The winning leg pays 1 USD per share, all losing legs pay 0. Resolution typically settles the entire NegRisk event at once.
Are NegRisk fees different from binary markets?
Same fee schedule as binary - 0% maker, 0.75-1.80% taker by category. The maker rebate also applies. The only practical difference is that you have N order books to manage instead of 1.
Can I hedge a YES position by buying the other NegRisk legs?
Yes - this is the NegRisk-specific hedge. If you are long one leg and want to lock in current PnL, buy the other legs in proportion. Net cost should be (1 - your YES leg price), modulo fees. We dont recommend it as a primary strategy because the fees usually eat the hedge edge.
