📁Order Types
A comprehensive guide to Ostium's seven order types, their triggering mechanisms, and execution behaviors.
Overview
Ostium supports seven distinct order types designed to provide traders with execution experiences similar to traditional markets. These order types are categorized into two fundamental execution mechanisms:
Market Orders — Triggered by the mid-price and executed at the bid/ask price or Price-After-Impact
Limit Orders — Triggered by the mid-price selected by the user and executed at the bid/ask price or Price-After-Impact
Price-After-Impact
Some pairs might have Dynamic Spreads enabled, meaning that instead of using the bid or ask price, trades execute at the Price-After-Impact, which adjusts in real time based on short-term net buy and sell pressure—allowing zero-spread execution under balanced conditions and applying impact costs only when order flow becomes one-sided. Click here learn more.
Open Trade Orders
Ostium supports three types of orders for opening positions:
Open Market
Trigger: Most recent mid-price (immediate execution)
Execution: At bid/ask price or Price-After-Impact
Classification: Market order
Behavior: Order is triggered immediately after the request is received onchain
Rationale: This is a textbook market order, providing immediate execution at the current market conditions
Open Limit
Trigger: At bid/ask price or Price-After-Impact crossing user's limit price
Execution: At bid/ask price or Price-After-Impact that crossed the limit
Classification: Limit order
Behavior: Ensures execution only occurs when the trade can be filled at the limit price chosen by user or better
Rationale: The mid-price crossing the limit is insufficient; execution only occurs when the actual trade price reaches the limit, ensuring the user gets their desired price or better
Open Stop
Trigger: Mid-price crossing user's stop price
Execution: At bid/ask price or Price-After-Impact
Classification: Market order
Behavior: Functions as a market order once triggered
Rationale: Follows market conventions where traders expect stop orders to be triggered as market orders. Traders can use limit orders instead if they want to ensure execution at specific prices
Close Trade Orders
Ostium supports four types of orders for closing positions:
Close Market
Trigger: Most recent mid-price (immediate execution)
Execution: At bid/ask price or Price-After-Impact
Classification: Market order
Behavior: Equivalent to Open Market order
Rationale: Provides immediate position closure at current market conditions
Take-Profit (TP)
Trigger: At bid/ask price or Price-After-Impact crossing user's TP price
Execution: At bid/ask or Price-After-Impact
Classification: Limit Close order
Behavior: Equivalent to Limit Open order
Rationale: Ensures position closure at a higher price in the future
Stop-Loss (SL)
Trigger: Mid-price crossing the user's SL price
Execution: At bid/ask or Price-After-Impact
Classification: Market order
Behavior: Equivalent to Limit Open order
Rationale: Ensures position closure at a lower price in the future
Liquidation
Trigger: Mid-price crossing the calculated liquidation price
Execution: At bid/ask or Price-After-Impact
Classification: Limit Close order
Behavior: Equivalent to Stop Loss order
Rationale: Ensures automatic position closure when margin conditions are breached. Uses limit-style execution to prevent unnecessary liquidations during transient volatility, while Ostium’s liquidation backstop mechanisms cover residual market risk.
Summary
Open Market
Market Open Order
Mid-price (immediate)
Bid/Ask or Price-After-Impact
Open Limit
Limit Open Order
Bid/ask price or Price-After-Impact crossing limit
Bid/ask price or Price-After-Impact
Open Stop
Market Open Order
Mid-price crossing stop
Bid/Ask or Price-After-Impact
Close Market
Market Close Order
Mid-price (immediate)
Bid/Ask or Price-After-Impact
Take-Profit
Limit Close Order
Bid/ask price or Price-After-Impact crossing TP
Bid/ask or Price-After-Impact impact
Stop-Loss
Limit Close Order
Mid-price crossing SL
Bid/Ask or Price-After-Impact
Liquidation
Limit Close Order
Mid-price crossing liquidation price
Bid/Ask or Price-After-Impact
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