Market Orders vs Limit Orders: How They Work in Order Books

Posted By Tristan Valehart    On 9 Jan 2025    Comments (19)

Market Orders vs Limit Orders: How They Work in Order Books

Market vs Limit Order Simulator

Market Order

Executes immediately at best available price. Guarantees execution but gives up price certainty.

Limit Order

Only executes at specified price or better. Gives price control but may never fill.

Trade Execution Summary

Click "Execute Trade" to see detailed results based on your selections.

Ever wondered why a trade sometimes fills in a split second while other times it sits idle in the order book? The answer lies in the difference between market orders vs limit orders and how they interact with the order book a real‑time list of buy and sell offers for a security.

Market Order an instruction to buy or sell immediately at the best available price prioritises speed. When you click “buy” at market price, the system matches your request against the best ask price the lowest price a seller is willing to accept for a buy, or the best bid price the highest price a buyer is willing to pay for a sell, and the trade happens instantly.

Limit Order an order that only executes at a specified price or better gives you price control. A buy limit sits below the current ask; a sell limit sits above the current bid. If the market never reaches your price, the order remains unfilled.

Liquidity the ability of the market to absorb trades without large price changes determines how much slippage you might see.

Slippage the gap between the expected price and the actual execution price is a common risk with market orders, especially in thinly traded assets.

Maker Rebate a credit exchanges give to traders who add liquidity by posting limit orders can offset some transaction costs for frequent limit order users.

Quick Takeaways

  • Market orders guarantee execution but give up price certainty.
  • Limit orders protect price but may never fill.
  • Liquidity and volatility dictate which order type is safer.
  • Understanding the order book mechanics helps you avoid unwanted slippage.
  • Mixing both types strategically can improve overall trade performance.

How Market Orders Consume the Order Book

When a market order arrives, the matching engine scans the best limit orders on the opposite side of the book. Each matched limit order is removed-this is called “taking” liquidity. If your buy market order needs 1,000 shares but the best ask only covers 300, the engine moves down the ladder, filling the remaining 700 at progressively higher ask prices. The final average price is a weighted blend of those levels, and the difference from the last‑quoted price is the slippage.

Because market orders are executed against existing offers, they are usually filled within milliseconds in modern electronic markets. High‑frequency traders exploit this speed, but the rapid consumption of liquidity can temporarily widen the spread, especially in volatile moments.

How Limit Orders Populate the Order Book

A limit order sits in the book until a matching market order or another limit order on the opposite side meets its price. By posting at a specific level, you become a “maker” of liquidity. Your order may sit for seconds, minutes, or the entire trading day, depending on price proximity and market activity.

When a maker order is eventually hit, the counter‑party “takes” the liquidity. Exchanges often reward makers with a rebate (the maker rebate mentioned earlier), encouraging a deep book that narrows spreads for everyone.

Decision Framework: When to Use Each Order Type

Think of the choice as a trade‑off between execution certainty and price control. Below is a quick matrix that helps you decide based on two common variables: market liquidity and urgency.

Market Order vs Limit Order - Quick Comparison
AttributeMarket OrderLimit Order
Execution SpeedImmediate (milliseconds)Depends on price movement
Price ControlNone - accepts best availableExact price or better
Slippage RiskHigher, especially in low‑liquidity marketsLow - but may never fill
Liquidity ImpactTakes liquidity, may widen spreadAdds liquidity, may earn rebate
Typical Use CasesUrgent exits, high‑volume stocks, market‑on‑closeTargeted entry/exit points, thinly traded assets, profit‑taking thresholds
Real‑World Examples

Real‑World Examples

Example 1 - High‑Liquidity Stock: Apple (AAPL) trades millions of shares per minute with a sub‑$0.01 bid‑ask spread. Placing a market buy for 200 shares will likely fill at $174.32‑$174.33 with negligible slippage. A limit buy at $174.00 could sit idle for hours because the price rarely dips that low.

Example 2 - Low‑Liquidity Crypto Pair: Consider the BTC/USDT pair on a smaller exchange where the best ask is $62,300 and the next level is $62,500. A market buy for 5 BTC will eat both levels, averaging $62,400 and leaving you $200 worse off than the quoted price-clear slippage. A limit buy at $62,250 protects you, but you might only fill 1BTC when the price briefly dips.

Example 3 - After‑Hours Trading: The S&P500 index futures close at 4:00PM EST. A market order placed at 4:15PM will execute at the opening price of the next session, which could be several points away-a classic after‑hours gap risk. A limit order set at the previous close price can guard against that gap, though it may sit unfilled until the market reopens.

Common Pitfalls & Pro Tips

  • Pitfall: Using market orders in thin markets and getting a terrible fill.
    Tip: Check the order book depth first; if the top three levels only hold a fraction of your size, switch to a limit order.
  • Pitfall: Setting limit prices too far from the current market, leading to no execution.
    Tip: Use technical support/resistance or a percentage of recent volatility (e.g., 1‑2× average true range) to gauge realistic limits.
  • Pitfall: Forgetting order expiration-limit orders can linger and tie up capital.
    Tip: Choose “day” or “good‑til‑canceled” intentionally, and review open orders daily.
  • Pitfall: Ignoring maker‑taker fee structures.
    Tip: On exchanges that rebate makers, you can offset commission costs by posting passive limit orders.
  • Pitfall: Relying on market orders during volatile news spikes.
    Tip: Consider “market‑if‑touched” or a small limit spread to avoid extreme slippage.

High‑Frequency Trading algorithmic strategies that execute thousands of trades in fractions of a second can compress spreads but also amplify slippage for large market orders during flash events.

Hybrid Strategies - Getting the Best of Both Worlds

Many platforms now offer order types that blend immediacy with price protection. A “market‑if‑touched” (MIT) order sits as a limit but becomes a market order once the price reaches a trigger. A “stop‑limit” order protects against large moves while still specifying a price ceiling. Using these tools lets you stay in control during fast markets without sacrificing execution certainty.

Quick Checklist Before You Hit “Send”

  1. Assess liquidity: Look at the depth of the order book for the size you want.
  2. Define urgency: Do you need to be in/out now or can you wait for a better price?
  3. Set realistic limits: Use recent volatility or support/resistance levels.
  4. Choose duration: Day vs GTC vs specific expiration.
  5. Mind fees: Check maker‑taker schedule; factor rebates into cost.
  6. Monitor after‑hours risk: Gaps can turn a market order into an expensive surprise.

Frequently Asked Questions

Can a market order guarantee the exact price I see on the screen?

No. A market order accepts the best available price at the moment the order hits the exchange. In fast markets the quoted price can shift by a few cents or even dollars before the trade is executed, which is called slippage.

What happens to a limit order that never gets filled?

It stays open until it expires, you cancel it, or the broker’s system automatically removes it at the end of the trading day (for “day” orders). While pending, the funds are held, which can affect buying power.

Do limit orders always get a maker rebate?

Only if the order adds new liquidity and is not immediately matched. If a limit order sits on the book and later gets filled, the exchange credits the maker rebate. If it’s filled instantly because another order already existed at that price, it’s considered a taker trade and no rebate is earned.

When should I prefer a limit order over a market order?

Use a limit order when price matters more than speed-such as setting a profit‑target, buying at a support level, or trading thinly‑liquid assets. Choose a market order when you need to exit fast, the asset is highly liquid, or you’re executing a large order that must be filled immediately.

How does high‑frequency trading affect my market order?

HFT firms compete to be the fastest takers, which can narrow spreads but also cause rapid price swings. In volatile moments, a market order may be filled across several price levels before you see the final execution price, increasing slippage.