Forex Slippage, Stop Orders, and Requotes Explained

A forex order can involve several prices that are easy to confuse. The request price is the quote or limit a trader submits against. A trigger price is the condition that activates a stop order. The fill price is the price actually recorded for all or part of an accepted order. These prices can match, but fast movement, a gap, the quote used to trigger the order, or the execution rules can make them differ.

Slippage measures the difference between a chosen reference price and the fill. It is not the same thing as the bid–ask spread: the spread is the distance between simultaneous bid and ask quotes, while slippage compares a fill with a reference. A chart may display a midpoint that was never available to buy or sell. Use a same-side executable quote and state the timestamp and method when comparing executions.

For a useful comparison, choose the side-specific quote nearest the order decision or submission: the ask for a buy and the bid for a sell. Record whether the benchmark is the quote at submission, arrival at the provider, or another defined point. Different benchmarks answer different questions; an arrival-price benchmark, for example, can separate the market move before receipt from later execution, but only if timestamps are reliable.

Using positive values for adverse slippage, the simple formulas are:

Buy slippage (pips) = (fill price − reference ask) ÷ pip size Sell slippage (pips) = (reference bid − fill price) ÷ pip size

Suppose a hypothetical EUR/USD buy uses an ask of 1.1000 as its reference and fills at 1.1004. With a 0.0001 pip size, the result is +4 pips, adverse to the buyer. For a hypothetical sell referenced to a 1.1000 bid and filled at 1.0997, the result is +3 pips, adverse to the seller. A negative result under this convention is price improvement. Many non-JPY pairs use 0.0001 per pip and many JPY pairs use 0.01, but confirm the instrument’s convention. These examples are arithmetic only, not observed quotes.

A market order prioritizes execution under the provider’s rules, not a guaranteed price. A limit order states a price boundary: a buy limit is generally placed at that price or lower, and a sell limit at that price or higher, subject to product rules. The order may not execute if the market does not offer the required price and available quantity. OANDA’s U.S. help page describes its market-order entry and execution checks; its details apply to that provider and account.

A stop order becomes active when the platform’s stated trigger condition is met. The trigger may use a bid, ask, or another defined quote, so check the specific contract and platform. Once triggered, a conventional stop is often handled as a marketable order; a gap or thin market can therefore produce a fill beyond the stop level. A stop-limit changes into a limit after its trigger: it adds a price boundary but can remain unfilled. IG’s stop-versus-limit guide and OANDA’s execution-risk guidance explain these trade-offs for their products. Neither a stop level nor an order label alone tells you the actual fill.

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Submitting, accepting, triggering, filling, and reporting are separate events. An accepted pending order is not yet a trade. A triggered stop may still be waiting for execution; a partial fill means only some quantity has traded; and a rejection means the requested order did not execute as submitted. A requote is a provider response that offers or reports a changed price under its procedure. Read the order confirmation and account history to establish what happened instead of treating a notification as proof of a complete fill.

The CFTC’s customer advisory concerns U.S. retail off-exchange forex: it warns that a customer may trade against a dealer that controls the platform and prices displayed there. That scope should not be generalized to every country, exchange-traded future, or execution model. Platform codes are also not universal definitions. For example, MetaTrader 5’s MQL5 documentation assigns separate return codes to requote (10004), rejection (10006), partial completion (10010), and changed prices (10020). Those are MT5 server responses, not standard status codes for all brokers. FOREX.com’s U.S. execution FAQ is likewise an example of one provider’s policy, including its optional price-tolerance handling.

A quote is observed at a point in time; execution takes place after an order is transmitted and processed. Prices can move during that interval, especially around economic releases, central-bank decisions, market openings, or a weekend gap. Available quantity can also change. If an order is large relative to accessible liquidity, different parts may fill at different prices or only partly, depending on the product and provider.

Slippage can be favorable or adverse. A buy can fill below its reference ask or a sell above its reference bid, creating price improvement under the sign convention above. Some providers describe both directions in their own execution disclosures; do not assume that every platform treats favorable and adverse movement symmetrically. Spread, commission, financing, and slippage are separate cost components, and a calculation from the midpoint can double-count or misstate them. OANDA’s educational guide describes stop execution and gap risk as provider-specific examples; the governing account terms determine the actual procedure.

Review the legal entity and product first: retail OTC forex, a CFD, and an exchange-listed currency future do not necessarily share the same execution rules or customer protections. Then look for the provider’s definition of requested and reference price, order trigger quote, execution priority, price tolerance or deviation setting, requotes, rejections, partial fills, and treatment during fast or unavailable markets. Check whether a price boundary applies before or after a stop trigger, and whether the provider can cancel, reject, or fill less than the requested size.

A provider’s phrase such as “best available price” is a description of its policy, not a guarantee that the requested price will be obtained. Compare like with like: the same pair, side, order type, size, session, and volatility conditions. Ask what the published execution statistics measure and whether they include positive and negative slippage, rejected orders, and partial fills. No single latency or slippage number proves that an account will receive the same outcome. Save the dated terms and the identity of the contracting entity because the platform brand alone may not identify the legal counterparty.

For each order, preserve the timestamp and time zone, pair, buy or sell side, requested size, order type, reference bid or ask, trigger level if any, actual filled quantity and prices, and final status. Calculate slippage per fill using the same benchmark rule, then summarize the distribution rather than relying on one average. Separate a no-fill, a rejection, and a requote from executed trades; including only successful fills can make execution look better than the full experience.

Pair the execution record with spread and commission data, and include financing separately when relevant. If the goal is an all-in comparison, use a consistent reference that does not count the spread twice. Forex spreads and commissions covers quoted trading costs, while forex trading hours and session overlaps helps label the market conditions. Lot size and pip value explains how pips map to account currency; margin and leverage covers a different risk dimension.

Execution quality cannot be inferred from the word “forex” or one screenshot. Compare the product terms, the sample conditions, and the actual account record. The examples here are hypothetical education, not a recommendation, a current broker ranking, or a promise of execution. Rules and protections depend on the product, contracting entity, and jurisdiction.

For a separate look at slippage in exchange-traded futures and related mechanics, see these guides:

• Forex Spread vs. Commission: How to Compare All-In Trading Costs
• Forex Market Hours and Session Overlaps: How the 24-Hour Week Works
• Forex Lot Size and Pip Value: Size a Position From Its Stop
• Forex Margin vs. Leverage: What the Numbers Actually Mean
• How Do You Calculate the Futures Bid-Ask Spread and Slippage?

Sources: CFTC customer advisory · FOREX.com Orders & Execution FAQs · OANDA market order entry · IG stop-versus-limit guide · OANDA slippage and execution risk · MetaTrader 5 trade-server return codes