Forex broker execution is the process that turns an order into a completed trade. The price displayed when you click, the price requested and the price eventually filled may differ. That difference can affect both the cost of entering a position and the loss incurred when closing it.
When comparing forex brokers, look beyond advertised spreads and execution speed. Assess how orders are priced, when they can be rejected, whether favourable price movements reach your account and what happens during fast markets. “No requotes” does not mean “no slippage”.
What happens between an order and a fill?
Your trading platform sends an instruction to the broker. The broker’s systems check whether the order meets account and trading conditions, then process it under the applicable execution rules. An order acknowledgement is not necessarily a completed trade: check the execution confirmation, filled quantity and price.
Spot foreign exchange operates over the counter rather than through one central exchange. Trading takes place across dealers and venues, with substantial activity handled within dealers’ own liquidity pools. The BIS research on FX trade execution documents this fragmented structure. A quote from another feed therefore provides a comparison point, not automatic proof that your broker could execute your order there.
Separate the broker’s customer transaction from any trade it makes to manage its own exposure. A broker hedging externally does not necessarily mean your order itself went to an exchange. Labels such as STP, ECN and “no dealing desk” are not substitutes for checking the contract, execution policy and actual fills.
How forex slippage changes a trade
Slippage is the difference between a reference price, such as the requested price, and the actual execution price. Negative slippage makes the fill worse for you; positive slippage improves it. For a buy, a higher fill is worse. For a sell, a lower fill is worse.
Consider a hypothetical GBP/USD purchase of £20,000. The available ask is 1.27000 when you submit the order, but the fill arrives at 1.27018. The difference is 0.00018, or 1.8 pips. Multiplying £20,000 by that exchange rate difference gives an additional entry cost of US$3.60, before any account currency conversion.
If the same purchase filled at 1.26990 instead, you would receive one pip of positive slippage, worth US$2 on that position. Slippage is not inherently a charge retained by the broker; it describes an execution outcome that requires explanation.
Keep it separate from the spread. Buying at the ask rather than the bid is not, by itself, slippage. Compare the fill with the correct side of the quote, then assess it alongside forex spreads, commissions and overnight charges. Otherwise, it is easy to count the same cost twice.
Requotes versus market execution
A requote occurs when the broker offers a replacement price instead of completing the order at the requested price. You can accept the replacement or decline it. Slippage, by contrast, describes the difference in the completed fill. Repeated requotes can also leave you without a position while the market moves.
In MetaTrader 5’s instant execution mode, an order can receive a requote when the price moves beyond the permitted deviation. In market execution mode, submitting the order authorises execution at the broker’s execution price without another price confirmation. These distinctions appear in the MetaTrader 5 execution mode documentation.
“Instant” is therefore a mode name, not a promise of zero delay. Nor does market execution guarantee that every order will succeed. Check which mode applies to the instrument and whether a deviation setting is supported. A setting labelled “maximum deviation” should not be assumed to protect every order type, particularly triggered stops.
How order types affect execution risk
Order choice determines whether you prioritise getting a trade completed or controlling its price. Those goals are not always compatible.
| Order type | Price instruction | Main execution risk |
|---|---|---|
| Market order | Trade at the available execution price. | The fill may differ from the displayed quote. |
| Limit order | Buy at the limit or lower; sell at the limit or higher. | The order may remain unfilled. |
| Ordinary stop order | Trigger an execution instruction when the stop condition is met. | The trigger price is not a guaranteed fill price. |
| Stop-limit order | Place a limit order after the stop condition is met. | A rapid move may leave the limit order unfilled. |
Check the instrument’s trigger rules, not just the chart. In MetaTrader 5 forex trading, purchases use the ask and sales use the bid. A short position’s stop can therefore trigger on the ask even if a bid-only chart never reaches that level. The platform’s order and trigger definitions distinguish these conditions.
A limit order controls the acceptable execution price, but does not solve the need to exit urgently. A stop-limit used as protection may leave a losing position open after a sharp move. Only treat a stop as price guaranteed when the contract expressly provides that protection, and check its restrictions and charges.
Why slippage increases in difficult markets
Slippage risk rises when prices change faster than orders can be processed or when insufficient trading interest exists at the requested price. Economic announcements, abrupt news and market reopening gaps deserve particular attention. The Financial Ombudsman Service guidance on stop execution identifies fast markets and opening gaps as circumstances in which stops may fill at worse prices.
Position size matters too. A displayed price does not necessarily represent enough available quantity for an entire order. Depending on the execution arrangement, an order may fill across several prices, fill partly or be rejected. Where several fills occur, assess the quantity weighted average price rather than selecting the best or worst individual fill.
Connection delays can also separate the quote you see from the market available when the order arrives. A faster connection may reduce that delay, but cannot manufacture liquidity. Equally, a low advertised processing time says little unless you know where measurement starts and ends.
What a UK execution policy should tell you
Best execution is not a zero-slippage guarantee
Where the FCA’s best execution rules apply, firms must take sufficient steps to obtain the best possible result, considering price, costs, speed, execution likelihood and other relevant factors. For retail clients, the assessment centres on total consideration: the instrument’s price plus execution-related costs. These duties are set out in FCA COBS 11.2A on best execution.
This is not a promise that every trade will match the price visible when you click. A worse fill needs to be assessed against the market conditions, order instructions and execution arrangements. Conversely, the existence of slippage risk does not excuse unfair treatment.
Read the policy for the legal entity holding your account. Identify how it sets prices, whether it acts as your counterparty, which execution venues it uses and how it handles rejected orders. Also check the treatment of partial fills, price improvements and alleged pricing errors. Broad claims about “excellent execution” answer none of those questions.
Positive and negative slippage deserve equal scrutiny
An execution policy that passes adverse movements to clients while retaining favourable movements raises a different issue from ordinary market slippage. The FCA’s 24 February 2014 final notice on FXCM’s execution practices records precisely this historical problem: customers received adverse movements while the group retained favourable ones.
That does not mean your account should show equal numbers of positive and negative fills. Order types, trading times and market behaviour affect the results. Stop orders and limit orders also impose different conditions. Investigate persistent adverse patterns, but do not treat a small sample of losing fills as proof of manipulation.
How to assess your broker’s execution
Start with records, not impressions. A memorable bad fill can dominate your view, while small improvements go unnoticed. If you already trade live, review the orders you would have placed anyway. Do not generate extra trades simply to produce an execution sample.
For each order, retain enough detail to reconstruct what happened:
- Instructions: currency pair, buy or sell, order type, requested quantity, requested price and any deviation setting.
- Timing: submission and confirmation timestamps, including time zone and the timestamp precision available.
- Outcome: filled quantity, execution prices, rejection messages, requotes and any later adjustments.
- Conditions: bid and ask quotes where available, spread, trading session and nearby economic announcements.
Use a demo account to learn the controls and practise retrieving these records. Do not treat simulated execution as proof of future live fills. The distinction is covered in what forex demo accounts can and cannot teach you.
Separate market entries, stop exits and limit orders before calculating averages. Then group comparable trades by pair, size and trading conditions. Mixing quiet-session EUR/USD orders with news-driven trades in a less liquid pair produces a number, but not a useful comparison.
Record the proportion of orders filled, rejected or requoted alongside slippage. A broker that rejects difficult orders may display attractive slippage figures for the trades it accepts. Those figures do not capture the opportunities missed or the delay involved in resubmitting.
Look beyond the average. Examine the largest adverse fills and whether they cluster around particular events. When comparing quoted execution speeds, ask whether the figures include rejected orders and measure the full request-to-confirmation interval. A fast fill at a poor price is still a poor fill.
Control the parts you can
Choose order types that fit the decision. If entry price matters more than participation, consider whether a limit instruction is appropriate. If exiting matters more than the exact price, recognise the remaining slippage risk rather than assuming a stop provides a fixed maximum loss.
Avoid initiating trades around scheduled announcements unless that exposure forms part of a tested plan. Check order confirmations before clicking again after a delay; a slow response is not proof that the first instruction failed. Keep connection problems and platform errors in your journal so they are not confused with broker pricing.
Do not widen stops simply to make execution statistics look better. That changes the trade’s risk rather than repairing execution. If your approach only works with perfect fills, reassess the approach.
What to do about a disputed fill
Ask the broker for an execution review while the details are fresh. Provide the order identifier, timestamps, requested price and actual fill. Request an explanation of the relevant bid or ask, the trigger event, any delay and the execution policy provision applied.
Preserve confirmations, platform logs, screenshots and the policy version that applied at the time. A screenshot from another provider may support your question, but it will not necessarily establish the executable price available for your order. Keep the complaint focused on the discrepancy you can document.
If the response does not resolve the issue, follow the formal process for complaining about a broker or investment firm. Distinguish ordinary market movement from an unexplained delay, an incorrect trigger, a pricing error or treatment inconsistent with the agreement. The objective is a documented explanation and, where justified, correction—not an assumption that every adverse fill must be refunded.