–

Intro

Use post-only orders on Sui Futures when you prioritize earning maker rebates over immediate execution and want to avoid accidentally taking liquidity from the order book. This order type ensures your order sits on the book side, contributing to market depth without crossing the spread.

Key Takeaways

• Post-only orders guarantee you receive maker fees when filled
• These orders auto-cancel if they would cross the spread
• Best suited for liquidity providers and long-term position builders
• Not ideal for time-sensitive entries or exits
• Reduces execution certainty in exchange for fee optimization

What Is a Post-Only Order

A post-only order is a limit order designed to rest on the order book without ever taking liquidity. According to Investopedia, maker orders add liquidity to exchanges by providing bid and ask prices for other traders to execute against. On Sui Futures, the post-only modifier enforces this behavior automatically—if your order would match immediately upon placement, the exchange cancels it instead.

The Sui blockchain’s object-centric model enables fast order matching and precise fee calculation, making post-only orders particularly efficient for high-frequency trading strategies on perpetual futures markets.

Why Post-Only Orders Matter

Post-only orders matter because they allow traders to systematically earn the spread between maker and taker fees. Most futures exchanges offer lower fees to market makers—sometimes 0.02% for makers versus 0.05% for takers. Over thousands of trades, this difference compounds significantly.

For professional traders on Sui Futures, post-only orders serve as a core tool for reducing effective trading costs. The BIS reports that algorithmic trading now accounts for over 60% of forex market volume, with maker-taker fee structures driving much of this activity.

How Post-Only Orders Work

The post-only order follows a simple decision logic:

IF Order Price ≥ Best Ask (for buys) OR Order Price ≤ Best Bid (for sells)
THEN Cancel Order
ELSE Place Order on Book

When you place a buy post-only order at $50,000 on a Sui Futures contract with best ask at $50,100, your order rests on the book at $50,000. You pay the maker fee (typically 0.02%) only if a seller crosses your price later. If BTC rises and the best ask moves to $49,900, your order would have crossed—instead, the system cancels it and you pay nothing.

The formula for net cost with post-only orders:

Net Fee = (Maker Rate × Notional) – (Spread Benefit × Probability of Fill)

Where spread benefit equals the difference between your order price and the next available price on the opposite side.

Used in Practice

Day traders use post-only orders when scalping small price movements between support and resistance levels. Place your buy post-only order slightly above current support, wait for buying pressure to push price toward your level, and collect maker fees as other traders hit your bid.

Swing traders employ post-only orders to build positions incrementally without paying taker fees. If you want 10 SOL equivalent of SUI futures exposure, place five post-only limit orders at increasing prices. Each fill earns you maker rebates while averaging into your position.

Arbitrageurs between spot and futures markets also rely on post-only orders. When futures trade at a premium to spot, place post-only sell orders to capture the premium without risking market orders that might move the spread unfavorably.

Risks and Limitations

Post-only orders carry execution risk. Your order may never fill if price moves away from your level, causing you to miss trading opportunities. This risk increases during high-volatility periods when spreads widen and price momentum accelerates.

The strategy requires patience and accurate price prediction. If you place post-only orders at unrealistic levels expecting a pullback that never comes, your capital remains locked and uninvested.

Additionally, in thinly traded Sui Futures markets, the maker rebate itself may be insufficient to justify waiting, especially when opportunity costs from unfilled orders accumulate over time.

Post-Only Orders vs Taker-Only Orders

Taker-only orders prioritize immediate execution by crossing the spread. You pay higher fees (typically 0.05-0.07%) but guarantee entry or exit. Post-only orders sacrifice execution certainty for lower fees (0.02%) and potential rebates.

For momentum traders entering breakout setups, taker orders make sense—you need confirmation fills immediately. For range-bound traders adding to positions at known support, post-only orders maximize profitability by collecting the spread difference.

The choice depends on your strategy time horizon and whether execution speed outweighs cost efficiency for your specific trading approach.

What to Watch

Monitor Sui Futures market depth before placing post-only orders. Wide bid-ask spreads reduce the viability of post-only strategies since the potential maker rebate must justify the execution risk of waiting.

Track your fill rates. If less than 40% of post-only orders fill, reconsider your price levels or switch to standard limit orders. The goal is consistent fills while capturing fee differentials.

Watch network congestion on Sui. The blockchain’s transaction finality affects order placement speed. During high-traffic periods, your post-only order might arrive after the market has already moved, increasing cancellation frequency.

FAQ

Can post-only orders be used with leverage on Sui Futures?

Yes, post-only orders function with leveraged positions on Sui Futures. Your margin requirements apply regardless of order type, but post-only orders help reduce overall trading costs when managing leveraged positions.

What happens if I cancel a post-only order before it fills?

You simply remove the order from the book with no penalty. Post-only orders have no additional cancellation fees beyond standard network gas costs on Sui.

Do post-only orders guarantee maker rebates?

Post-only orders guarantee you will not pay taker fees, but rebates depend on whether your order eventually fills. If the order stays unfilled and expires, you receive neither maker rebates nor taker fees.

Can I place post-only orders during market open?

Yes, post-only orders work during all trading sessions. During high-volatility opens, your orders face higher cancellation risk as prices gap beyond your specified levels.

How quickly do post-only orders execute on Sui?

Sui’s high-throughput blockchain processes order updates within milliseconds. However, actual fill timing depends on market conditions and whether your price level attracts counterparty liquidity.

Are post-only orders available for all Sui Futures pairs?

Most Sui Futures trading pairs offer post-only order options, but availability depends on your exchange. Verify post-only support for specific trading pairs before planning your strategy.

What is the minimum order size for post-only orders?

Minimum order sizes vary by exchange and trading pair. Generally, Sui Futures follow standard minimum notional requirements that apply to all order types including post-only.