Market vs Instant Execution in Forex: What’s the Difference?

Market vs Instant Execution: The Quick Answer

The market vs instant execution question comes down to one thing: who controls the fill price. With instant execution, your order carries the price you clicked. The broker either fills you at that price (or within your allowed deviation) or refuses and sends back a requote with new prices. With market execution, sending the order means you agree in advance to be filled at whatever price the broker’s server has at the moment of execution — no requotes, but no price guarantee either.

Quick verdict: if you run expert advisors, scalp, or trade news, market execution is almost always the better fit because there is no requote rejection loop to break your strategy — you just need to accept and manage slippage. Instant execution gives you price certainty on every fill, but at the cost of rejected orders whenever the market moves against your quoted price. Crucially, you don’t choose the mode in your terminal: it is a broker-side setting tied to your account and symbol, so “choosing” a mode really means choosing the right account type.

What “Execution Mode” Means in MetaTrader

In MT4 and MT5, the execution mode is a property of the trading symbol set by your broker — not a setting you toggle. Which mode applies depends on the instrument type and the broker. The same platform can serve one symbol with instant execution and another with market execution, and two brokers can configure the identical symbol differently.

MetaQuotes defines several modes. MT4’s official product page lists three execution modes alongside two market orders and four pending order types. MT5 exposes four modes programmatically: instant, request, market, and exchange execution. The two you will actually encounter on retail forex accounts are instant and market. Request execution is the legacy ancestor of instant execution: the terminal first requests prices from the broker, then you confirm or reject the deal at the quoted prices, which stay valid for only a few seconds. Exchange execution applies to exchange-traded instruments on MT5, where orders go to an external trading system, and is outside the scope of a forex comparison.

Because the mode is baked into the symbol settings on the server, the practical decision for you as a trader happens at account-opening time. ECN and STP-style accounts are typically configured for market execution, while classic dealing-desk accounts historically used instant (or request) execution.

How Instant Execution Works

Under instant execution, the platform attaches the current price to your order before sending it. Per the official MT5 documentation, the order is executed at the price offered to the broker: if the broker accepts that price, the order goes through. Your fill price is the price you saw — that is the entire point of the mode.

The catch is what happens when the market moves while your order is in flight. This is where the Deviation field on the order ticket comes in. Deviation is the difference between the order execution price and your specified price that you are willing to accept. If the server’s current price is within your deviation tolerance, the order fills. If the price has moved beyond it, the dealer or server can refuse the order and offer new execution prices instead — a requote. Those new prices are valid for a few seconds only; you either accept them or the order dies. The larger the deviation you allow, the less likely you are to receive a requote.

For algorithmic traders the same mechanics surface in code. In MQL4, the OrderSend() function takes an explicit slippage parameter — the maximum price slippage you accept for buy or sell orders. If your requested price is outdated but still present in the price stream, the order fills at the current price only when that price sits within your requested price plus or minus the slippage value. If the requested price is fully out of date, the server returns error 138 (ERR_REQUOTE) regardless of your slippage setting. Any EA built for an instant-execution account must handle that error, or it will silently fail to trade exactly when the market is moving fastest.

How Market Execution Works

Market execution flips the logic. As the MT5 documentation puts it, the broker makes the decision about the order execution price without any additional discussion with the trader — and sending an order in this mode means advance consent to execution at that price. Your order says “fill me now at your current price,” not “fill me at this price or don’t.”

Two consequences follow. First, requotes disappear entirely: there is no quoted price for the server to defend, so there is nothing to re-quote. Second, the price you get can differ from the price you saw when you clicked. That difference is slippage, and it cuts both ways — if the market ticks in your favor between click and fill, you can receive a better price than expected; if it ticks against you, a worse one. Market execution trades price certainty for fill certainty.

Market execution also constrains how partial fills are handled. In this mode the available fill policies are Fill or Kill (execute the full volume or nothing), Immediate or Cancel (execute what’s available, cancel the rest), and Book or Cancel where the server enables it. The Return policy — where an unfilled remainder stays working as an order — is explicitly not allowed in market execution mode per the MQL5 reference.

Market execution is the standard on ECN/STP-style accounts, where the broker is passing your order into a live liquidity pool and cannot promise a specific price. One practical quirk to know: on some MT4 market-execution accounts, stop loss and take profit cannot be attached at order entry and are added by modifying the position after the fill — worth checking with your broker if your workflow or EA depends on SL/TP being set in the initial order.

Instant vs Market Execution Side by Side

Here is the full trade-off in one table. Note the pattern: instant execution protects the price and sacrifices the fill; market execution protects the fill and sacrifices the price.

Criteria	Instant Execution	Market Execution
Price you get	The price attached to your order (within your deviation), or no fill	The broker’s current price at the moment of execution
Requotes possible?	Yes — server can refuse and offer new prices, valid a few seconds	No — sending the order is advance consent to the fill price
Slippage possible?	Only within the deviation tolerance you set	Yes — can be negative or positive
SL/TP at entry	Attached with the order	On some MT4 accounts, added after the position is opened
Fill policies (MT5)	Fill or Kill, Immediate or Cancel, Return	Fill or Kill, Immediate or Cancel (Return not allowed)
Typical account type	Classic dealing-desk / standard accounts	ECN / STP-style accounts
Best for	Traders who want price certainty and accept rejected orders	EAs, scalpers, news traders who need fills, not requote dialogs

Which Mode Is Better for Your Trading Style?

For scalpers and news traders, market execution is usually the practical choice. During a volatile spike, an instant-execution account can trap you in a requote loop: you click, the price has moved, you get a requote valid for a few seconds, you accept, the price has moved again. Market execution guarantees you get into (and, more importantly, out of) the trade — but it shifts the burden of slippage control onto your strategy: sensible order sizing, avoiding the worst seconds of a news release, and monitoring your average fill quality.

For EA users, the case is even clearer. Most modern expert advisors are written and tested against market-execution (ECN-style) accounts — and execution differences are a leading reason an EA that wins in backtests loses live. An EA that never checks for error 138 will malfunction on an instant-execution account the moment volatility picks up — orders rejected, positions left unhedged, grids left half-built. If you must run an EA on instant execution, verify it handles requotes and uses a sensible slippage parameter in its OrderSend() calls.

The Latency Factor in Both Modes

Whichever mode your account uses, one variable makes both failure cases worse: the round-trip time between your terminal and the broker’s trade server. As the SEC’s investor education material puts it, trade execution isn’t instantaneous — prices can change quickly, and the price at execution may not be the price you expected. The longer your order is in flight, the further the market can move before the server processes it. On instant execution, that means more requotes; on market execution, it means larger slippage in either direction.

You cannot eliminate that window, but you can shrink it. Trading from a machine hosted close to your broker’s servers cuts the order round trip from hundreds of milliseconds to single digits, which directly reduces how stale your price is by the time it reaches the server. This is the main reason serious EA users and scalpers run their platforms on a low-latency forex VPS near their broker rather than from a home connection.

Conclusion: Pick the Account, Not the Setting

Instant execution means “fill me at my price or requote me.” Market execution means “fill me now at your price.” Neither is a toggle in your terminal — the mode is set per symbol by your broker, so the real decision is which account type you open. For discretionary traders who value knowing their exact entry price, instant execution still has a case. For EAs, scalpers, and anyone trading fast markets, a market-execution account paired with a low-latency setup — start by checking your broker’s latency — is the combination that keeps orders filling when it matters.

Whatever mode you trade, remember that requotes and slippage are both symptoms of the same disease: price movement during the order round trip. Reduce the round trip, and you reduce both.

FAQ: Market vs Instant Execution

Can I switch my account from instant to market execution?

No. The execution mode is a symbol property configured on the broker’s server — it depends on the instrument and the broker, and there is no terminal setting to change it. If you want the other mode, you need a different account type (or a different broker); ECN/STP-style accounts generally mean market execution.

Does market execution mean zero slippage?

No — it means zero requotes. Because you consent in advance to the broker’s execution price, the fill can land above or below the price you saw. Slippage on market execution can be negative or positive; what you gain is certainty that the order will actually execute.

Which mode do ECN brokers use?

Market execution. An ECN or STP broker routes orders into a live liquidity pool and cannot guarantee a specific price in advance, so its accounts are configured for market execution — you are filled at the best available price, with possible slippage in either direction.

What is a requote exactly?

A requote happens on instant (and request) execution when the price has moved beyond your allowed deviation before the server can fill your order. Instead of filling it, the server refuses the order and offers new execution prices, which remain valid for only a few seconds. You can accept the new price or let the order lapse. In MQL4 code, a fully outdated price surfaces as error 138 (ERR_REQUOTE).

Is instant execution faster than market execution?

No — the name is misleading. “Instant” refers to how the price is handled (your order carries a price and fills at it or not), not to execution speed. In practice a requote adds a full extra round trip plus your reaction time, so instant execution can easily be the slower path to a completed fill in a fast market.