A-Book Broker vs B-Book Broker. The Key Differences between the two Forex Models

In the Forex trading world, there are two primary business models: A-Book Broker (Non-Dealing Desk) and B-Book Broker (Market Maker). They define the way Brokers provide liquidity for transactions made by clients on their trading platform. In other words, each Broker needs to decide if they want to be an intermediary or a counterparty for them. However, it doesn’t mean that these two models are mutually exclusive; neither are they the only options.

A cover of a blog post explaining the differences between the A-Book Broker and B-Book Broker model

What is an A-Book in the Forex Business?

What’s the difference between an A-Book Broker and a B-Book Broker? A-Book is a type of Forex execution model. It is also known as an STP (Straight Through Processing) Broker or a Non-Dealing Desk Broker.

An A-Book Broker earns money by charging commission or making a slight change in spreads. It works through bridges that connect traders’ terminals directly to FX liquidity providers.

A-Book Brokers pass the orders directly to their FX Liquidity Providers. Depending on the setup of a particular LP, they can stay within their liquidity pool or get passed to other LP’s pools. A liquidity pool consists of many FX liquidity providers acting as a counterpart to the trades flowing out from a Forex Broker.  

A-Book Brokers make money by increasing the spread or charging commissions on the volume of orders. Therefore, there are no conflicts of interest; they earn the same amount of money with both winning and losing traders. They do not take many risks but potentially achieve lower profits because they earn only on margins/commissions.

The A-Book Broker model (NonDealing Desk) operates as a middleman between the trader and the market. By choosing to deal through an A-Book Forex Broker, the trader cuts out both the market maker and their dealing desk, removing, as a consequence, the parties that would otherwise profit from their transactions.

What Are the Advantages of Trading with an A-Book Broker?

The main advantage of trading with an A-Book Broker is a smaller number of conflicts of interest, as the profit of their clients does not have a negative impact on their business.

In this model, prices are acquired from several market participants instead of just one Broker liquidity provider. This can lead to better fills, tighter dealing spreads and more accurate quotes. Especially when compared with the service provided by a Forex Broker that has only a single source for its quotations.

Usually, traders prefer to execute their trades through an STP (A-Book) Broker model, not the B-Book Broker, as it often requires no Dealing Desk. This way, FX Brokers are more transparent with clients’ trades. That’s because the client is entering trades into an actual market, instead of an artificial one (possibly created by a Market Maker).

There are also some downsides to trading with an A-Book Broker. As orders are processed directly to the liquidity pool, traders witness variable spreads. Those spreads can be very tight when liquidity is high, but they can vary significantly during low-volume periods. 

That becomes even more noticeable when someone trades financial derivatives on exotic currency pairs such as the USDNOK or EURZAR.

Additionally, it is worth mentioning that you can see the spreads on such currency pairs tighten during regular market hours. Nevertheless, during off-market hours (such as the early Asian trading session), you will experience precisely the opposite, meaning that spreads will probably widen.

How Does a B-Book Broker Work?

The B-Book Broker model is also called Market Maker. Unlike an A-Book Broker, a B-Book Broker chooses to trade against their clients. There is no external liquidity pool where the Broker executes trades. In this case, it acts as a counterparty to his trades. 

In simple terms, if a trader places a buy order, the Broker will be selling to them and vice versa. Thus, it is clear that this type of model generates conflicts of interest between the B-Book Broker and their clients.

However, in certain instances, trading with a B-Book Broker could be beneficial for traders. For example, traders can get guarantee fills on their trades. In addition, even when liquidity is low, traders get a good execution of orders because the Broker acts as the market maker.

Another good reason to choose a B-Book Broker instead of an A-Book Broker is that the B-Book model offers fixed spreads no matter if you trade during peak market hours or off-market hours. A B-Book Broker typically charges a fixed spread you pay every time you open or close a position. This, again, has some advantages and drawbacks. For one, having fixed spreads makes it easier to trade when there are market shocks. But at the same time, you will have to improve your trading strategy to account for the fixed spreads.

That’s why FX Brokers with larger market makers use a hybrid model. It involves placing transactions in A-Book or B-Book based on traders’ profiles.

Hybrid Models: A-Book Broker and B-Book Broker Combined

The popularity of the hybrid model is understandable because it allows FX Brokers to increase their profitability and credibility. It also allows Brokers to earn money from profiting traders by sending their trading orders to liquidity providers without generating conflicts of interest.

To successfully identify profitable and unprofitable investors, Forex Brokers have software that analyzes their clients’ orders. For example, they can filter traders by the amount of their deposit, the leverage used, the risk taken with each transaction, and the use or non-use of protective stops.

The hybrid model does not have to be bad for traders either. After all, the profits gained from traders placed in the B-Book allow hybrid Brokers to provide all their clients with very competitive spreads. That’s true whether they are profitable or not. However, if a hybrid Broker manages the risk of the B-Book poorly, they can lose money and thereby threaten the company. That is perhaps the biggest disadvantage of this system.

The hybrid model may function in the following ways:

  • The Broker can divide their customers. Send some of the customers to their FX Liquidity Provider and keep others in-house.
  • The Broker can divide customers’ trades. Keep some trades in-house and send others to their FX Liquidity Provider.
  • The Broker can decide to send all trades of a specific size to the FX Liquidity Provider and keep the rest in-house.

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