Limit vs Market Order

Limit vs Market Order

Every trade you make on an exchange uses one of two fundamental order types: a limit order or a market order. Choosing the right one affects your execution price, fees, and overall trading costs.

What is a Market Order?

A market order executes immediately at the best available price. When you place a market buy order, you purchase the asset at the current lowest ask price. When you place a market sell order, you sell at the current highest bid price.

Advantages:

• Guaranteed execution (as long as there is liquidity).
• Instant fill, no waiting.
• Simple to use.

Disadvantages:

• You have no control over the exact price you get.
• You pay the spread.
• Subject to slippage in thin or volatile markets.
• Higher trading fees (taker fee).

What is a Limit Order?

A limit order specifies the exact price at which you want to buy or sell. A limit buy order will only execute at your specified price or lower. A limit sell order will only execute at your specified price or higher.

Advantages:

• Full control over your execution price.
• No slippage.
• Lower trading fees (maker fee).
• You add liquidity to the order book.

Disadvantages:

• No guarantee of execution. If the price never reaches your limit, the order remains unfilled.
• Partial fills are possible in low-liquidity conditions.
• Requires patience and planning.

What is Slippage?

Slippage is the difference between the price you expected and the price you actually received. It occurs with market orders, especially when:

• The order is large relative to available liquidity.
• The market is volatile and prices are moving fast.
• The order book is thin with few orders at each level.

Example: You place a market buy order for 10 ETH. The order book has 3 ETH at $2,000 and 7 ETH at $2,001. Your average fill price is $2,000.70, not $2,000. The $0.70 difference is slippage.

With a limit order at $2,000, you would only buy the 3 ETH available at that price (or wait for more liquidity to appear). No slippage, but potentially an incomplete fill.

Time-in-Force Options

When placing a limit order, you can specify how long it remains active:

GTC (Good Till Cancelled)

The order stays on the book until it is either filled or you manually cancel it. This could be minutes, hours, days, or weeks. GTC is the most common time-in-force for grid bot orders, as the bot places limit orders and waits for the price to reach them.

IOC (Immediate or Cancel)

The order attempts to fill immediately. Any portion that cannot be filled instantly is cancelled. This is useful when you want to buy at a specific price but do not want the order lingering if the price moves away.

FOK (Fill or Kill)

The entire order must fill immediately, or it is cancelled entirely. No partial fills are accepted. This is less common but useful when you need all-or-nothing execution.

Post-Only

The order is guaranteed to be placed on the book as a maker order. If it would cross the spread and execute as a taker order, it is automatically cancelled. This ensures you always pay maker fees.

Which Order Type Do Grid Bots Use?

Grid bots primarily use limit orders with GTC time-in-force. Here is why:

1. Buy orders are placed as limit orders at specific grid levels below the current price. They wait on the order book until the price drops to their level.
2. Take-profit orders are placed as limit sell orders at the next grid level above each filled buy level. They wait until the price rises to that point.

By using limit orders, grid bots:

• Pay lower maker fees instead of higher taker fees.
• Avoid slippage entirely.
• Add liquidity to the market.
• Execute at precise, predictable prices.

The only exception might be during bootstrap or shutdown, when market orders may be used for immediate execution.

Summary

• Market orders execute instantly at the current best price but are subject to slippage and higher taker fees, while limit orders execute at your specified price with no slippage and lower maker fees.
• Slippage occurs when your actual fill price differs from the expected price, most commonly with large orders in thin or volatile markets.
• Grid bots use GTC limit orders for precise execution at grid levels, ensuring lower fees and no slippage during normal operation.

Next Step

The fee difference between limit and market orders leads us to an important concept: Maker vs Taker