When you place a trade with a forex broker, what happens to your order next determines whether your broker is working with you or against you. This is not a trivial distinction, it affects your execution quality, the prices you receive, and whether your broker has a financial incentive for you to lose money.
Straight Through Processing (STP) is an execution model where your order passes directly through to external liquidity providers without intervention from a dealing desk. Understanding STP, what it means, how it compares to other models, and how to verify that a broker actually operates this way, is essential knowledge for any trader who cares about fair execution.
How STP Order Routing Works
The STP process follows a clear path:
- You place an order, for example, a market order to buy 1 lot of EUR/USD
- The broker's system receives your order and queries its connected liquidity providers for the best available price
- Multiple liquidity providers submit quotes, the broker's aggregation system selects the best bid and ask from the available pool
- Your order is filled at the best available price, and the broker simultaneously opens a matching position with the liquidity provider
- The broker earns revenue through a small markup added to the raw spread, or through a fixed commission per lot
The entire process happens electronically in milliseconds. No human dealer reviews your order, no one decides whether to accept or reject it, and the broker does not take the opposite side of your trade.
STP vs. Dealing Desk (B-Book) Brokers
To understand why STP matters, you need to understand the alternative.
A dealing desk (DD) broker, also known as a market maker or B-book broker, takes the opposite side of your trade internally. When you buy, the broker sells to you from its own inventory. When you lose, the broker profits directly. When you win, the broker loses.
The practical differences are significant:
| Feature | STP (A-Book) | Dealing Desk (B-Book) |
|---|---|---|
| Counterparty | External liquidity provider | The broker itself |
| Conflict of interest | No | Yes, broker profits from your losses |
| Spread type | Variable (depends on market) | Often fixed or semi-fixed |
| Requotes | Rare | More common in volatile conditions |
| Order rejection | Minimal | Possible, especially for profitable traders |
| Revenue source | Spread markup or commission | Net client losses + spread |
| Price transparency | Higher | Lower |
| Scalping restrictions | Generally none | Some brokers restrict scalping |
Advantages of STP Execution
No Conflict of Interest
This is the primary advantage. An STP broker earns the same revenue whether you win or lose, their income comes from spread markups or commissions on volume. This means the broker has a financial incentive for you to trade more and trade profitably (so you continue trading), rather than an incentive for you to lose.
Better Price Discovery
STP brokers aggregate prices from multiple liquidity providers, typically 10-25 or more. Competition among these providers tends to produce tighter spreads, especially during high-liquidity periods like the London-New York session overlap. You benefit from the competitive dynamics of the interbank market.
No Requotes
Because your order is matched against live liquidity rather than a dealer's discretion, requotes are extremely rare with genuine STP brokers. Your order is filled at the available price or not at all, there is no dealer deciding whether to honor a price.
Scalping and Strategy Freedom
STP brokers typically impose no restrictions on trading strategies. Scalping, news trading, hedging, and high-frequency approaches are all generally permitted because the broker's revenue model is not threatened by profitable trading.
Disadvantages of STP Execution
Variable Spreads
Because STP brokers pass through raw market prices (with a markup), spreads fluctuate based on market conditions. During low-liquidity periods (Asian session lulls, major holidays), spreads can widen significantly. During high-impact news events, spreads may spike to 5-10 times their normal level. If you are used to fixed spreads from a dealing desk broker, this variability can be surprising.
Potential for Slippage
STP execution means your order is filled at the best available price in the market, but in fast-moving conditions, that price may differ from what you saw when you clicked. This is slippage, and it occurs with any market order on any exchange. STP brokers are transparent about this; dealing desk brokers may absorb slippage internally (sometimes to your benefit, sometimes not).
Higher Minimum Deposits
Some STP brokers require higher minimum deposits than dealing desk brokers, typically $200-500 compared to $10-50 at some market maker brokers. This reflects the different business model: STP brokers need sufficient volume to be profitable, which correlates with larger account sizes.
How to Verify a Broker Is Truly STP
This is where critical thinking is essential. Many brokers claim to be STP or "No Dealing Desk" as a marketing label without fully operating that way. Here is how to verify:
Check Regulatory Filings
In the UK, the FCA requires brokers to publish order execution policies and annual best execution reports (RTS 28 reports). These documents reveal how and where orders are actually executed. In the EU, MiFID II imposes similar requirements. Request and read these documents, they are often available on the broker's website under legal disclosures.
Test Execution Quality
- Compare spread data against known raw spreads from interbank feeds. If the broker's spreads are consistently wider than the interbank market plus a reasonable markup, question the execution model
- Monitor slippage symmetry, in a genuine STP model, slippage should be roughly symmetric (positive and negative slippage occur at similar rates). If you only experience negative slippage, the broker may be manipulating fills
- Test during news events, genuine STP brokers will have wider spreads during news (reflecting the actual market), while dealing desk brokers may maintain tighter spreads but reject orders or requote
Ask Specific Questions
- "Who are your liquidity providers?", A real STP broker can name them (major banks, prime brokers, or ECN pools)
- "Do you B-Book any client orders?", Honest brokers will acknowledge hybrid models
- "Can I see your execution statistics?", Regulated brokers in the EU and UK are required to publish these
Check for Restrictions
If a broker restricts scalping, limits the number of trades per day, or prohibits certain strategies, these are indicators of a B-Book model. STP brokers have no reason to restrict profitable trading strategies.
Regulatory Requirements
Major regulators have established rules around order execution quality:
- FCA (UK): Requires best execution under MiFID II. Brokers must demonstrate they take "all sufficient steps" to obtain the best possible result for clients
- CySEC (EU): MiFID II best execution obligations apply. Annual RTS 28 execution quality reports are mandatory
- ASIC (Australia): Requires brokers to manage conflicts of interest and disclose their execution arrangements
- CFTC/NFA (US): Forex dealers must disclose their role as counterparty and maintain strict capital adequacy requirements
These regulatory frameworks do not prohibit dealing desk models, they require disclosure and fair treatment. The key is that you, as a trader, understand which model your broker uses.
Key Takeaways
- STP (Straight Through Processing) routes your orders directly to external liquidity providers without dealing desk intervention, eliminating the conflict of interest inherent in B-Book models.
- The broker earns revenue through spread markups or commissions, not from your losses. This alignment of incentives is the core advantage.
- Variable spreads are the trade-off, STP spreads reflect real market conditions, which means they widen during low liquidity and news events.
- Many brokers use hybrid models, routing some orders through STP and internalizing others. Read regulatory filings and execution policy documents to understand your broker's actual model.
- Verify STP claims by checking regulatory disclosures, testing execution quality, and asking specific questions about liquidity providers and B-Book practices.
- No execution model is inherently "better", but understanding the model helps you choose a broker whose incentives align with your own trading goals.
This lesson is for educational purposes only. It does not constitute financial advice. Trading forex involves significant risk of loss and is not suitable for all investors.