Définition
tick_size_change event
A WebSocket event signalling that the minimum price increment (tick size) for a market changed.
Definition
A tick_size_change event is a WebSocket event emitted by Polymarket when the market's minimum price increment (tick size) changes. It signals that the granularity traders can quote or place orders at has tightened or loosened for that instrument.
In context
On Polymarket the tick size is normally $0.01 and tightens to $0.001 as prices approach extremes. The WebSocket emits tick_size_change when an outcome's price crosses the boundary that triggers the tighter tick (for example moving above $0.96 or below $0.04) or when it moves back inside the wider range. Subscribe to the Market WS (wss://ws-subscriptions-clob.polymarket.com/ws/market) to receive real-time tick_size_change events alongside other market updates.
Why it matters
- Execution precision: A smaller tick allows orders at finer price increments and can reduce rounding inefficiencies when constructing multi-leg trades.
- Strategy impact: Algorithms that rely on discrete price grids must adapt their price steps when tick_size_change occurs.
- UI and reporting: Displays showing price ladders, spreads, or order books should react to keep quoted levels valid.
See also
- /glossary/tick-size