Polymarket Bot Tutorial · Chapter 22 of 32

NegRisk multi-outcome bots on Polymarket: sum-to-1 mechanics, leg arbitrage when YES legs dont sum to 1, hedging across legs, and execution pitfalls specific to multi-outcome markets.

By Harley Young, lead writer at Polymarkets.co.il. Last reviewed: May 2026.

What this chapter covers

This is chapter 22 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.

  • NegRisk vs binary recap
  • Sum-to-1 invariant and arbitrage
  • Leg-by-leg hedge construction
  • Execution: neg_risk flag in orders
  • Common bugs in NegRisk bots
  • Code: snapshot all legs and detect under-1.00 sum

NegRisk vs binary recap

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Sum-to-1 invariant and arbitrage

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Leg-by-leg hedge construction

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Execution: neg_risk flag in orders

This section is in active development. Want to be notified when it goes live? Contact us or watch the authors page.

Common bugs in NegRisk bots

This section is in active development. Want to be notified when it goes live? Contact us or watch the authors page.

Code: snapshot all legs and detect under-1.00 sum

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 the sum-to-1 invariant in NegRisk markets?
Across all YES legs of a NegRisk multi-outcome market, the sum of YES prices stays near 1 USD because exactly one outcome wins. If the sum drops below 1.00 net of fees, buying every leg in proportion locks in arbitrage profit. The arb is rare and gets sniped fast - treat as a curiosity, not a primary strategy.
How is NegRisk pricing different from binary?
Binary: YES price is your direct probability estimate. NegRisk: YES price for one leg is the probability of that specific outcome winning across N alternatives. As N grows, individual prices shrink (probabilities sum to 1). Trading NegRisk requires thinking in relative probabilities, not absolute Yes/No.
What is the most common NegRisk bot bug?
Forgetting the neg_risk: true flag in order placement. The order either rejects or routes to the wrong CTF position. We hit this in production - commit 06deaef in our trader history was specifically the fix. Always set neg_risk=true (Python) or negRisk: true (Node) on NegRisk orders.
Can I make money on NegRisk by hedging legs?
In theory yes (lock in spread between two legs). In practice the fees eat the hedge edge for most retail bots. Hedging works for keeping inventory neutral while market making, not as a standalone strategy.
How do I find NegRisk markets?
Filter gamma /events for events with markets count > 2 and the negRisk flag set. Common categories: championship winners (NBA Finals MVP), election fields (next Speaker), tournament brackets. Each gamma event includes its child markets array.
Are NegRisk markets more or less liquid than binary?
Less per leg, more in aggregate. A 30-team NBA Champion event might have 50K total 24h volume but each team market has only 1.6K - making per-leg trading harder. The aggregate liquidity is real, just fragmented.