If you are planning to launch a brokerage, one question comes up fast: what happens to your clients’ trades after they click “buy”?
The answer to that question is your execution model. And it is not just a technical decision — it determines how you make money, what risks you carry, and how regulators view your operation. Most aspiring broker operators encounter the terms A-book, B-book, and hybrid without a clear explanation of what each actually means for the business. This guide breaks it down plainly.
What Execution Models Actually Mean
When a client places a trade on your brokerage, one of two things happens with that trade:
You send it to a liquidity provider (LP) — an institutional bank or prime broker who takes the other side. You earn a spread or commission on the transaction. The LP holds the market risk. This is A-book execution.
You hold the trade on your own book — you are the counterparty. If the client loses, you profit. If the client wins, you pay. This is B-book execution.
A hybrid model does both, routing different clients or different trade types to different execution paths based on rules you define.
Neither model is inherently better. Each has a different profit logic, risk profile, and operational requirement. Choosing the wrong one for your stage and client base creates problems that compound over time.
A-Book: The Straight-Through Model
In a pure A-book operation, every client trade is sent directly to a liquidity provider. Your brokerage earns the spread between the raw LP price and the price you offer your client — the mark-up — plus any per-lot commission you charge.
How the revenue math works: Say you connect to an LP offering EUR/USD at a 0.2 pip raw spread. You offer clients a 1.2 pip spread. Your gross revenue per lot is 1.0 pip, or approximately $10 per standard lot. At 5,000 lots per month, that is $50,000 in gross spread revenue before operational costs.
The advantages of A-book:
- No market risk on client positions. Whether your clients win or lose, you earn the same mark-up.
- Regulatory favorability. A-book models are viewed more favorably in most jurisdictions because there is no conflict of interest between broker profitability and client success.
- Scalable. As client volume grows, revenue grows proportionally without increasing risk exposure.
The practical requirements: A-book execution requires a real-time connection to one or more LPs, a bridge or routing layer that sends orders in milliseconds, and enough monthly volume to meet LP minimum flow requirements. Most institutional LPs have volume thresholds; operators below those thresholds pay higher raw spreads or cannot access prime liquidity directly.
For a new brokerage, this is the most common friction point. LP access without scale is expensive. The spread economics deteriorate when you are paying 0.8 pip raw on a 1.2 pip retail offering, leaving only 0.4 pip gross margin per lot.
B-Book: The Market Maker Model
In a B-book model, your brokerage does not route trades externally. You are the market maker — taking the opposite side of every trade. When a client loses, the loss transfers to your book as profit. When a client wins, you pay the client from your reserves.
How the revenue math works: B-book profitability depends on client win/loss ratios. Industry data consistently shows that the majority of retail forex clients are net losers over rolling 12-month periods. A B-book operator with a client base that mirrors those averages generates revenue from the aggregate of client losses, minus the amounts paid to winning clients, minus operational costs.
The risk profile: B-book is not a guaranteed profit model. A client base that is disproportionately profitable — skilled traders, arbitrageurs, or algorithmic accounts — will systematically extract value from an unmanaged B-book. The broker absorbs those losses directly.
A well-run B-book requires active risk monitoring: identifying which clients are consistently profitable, routing those clients’ flow to A-book (or rejecting certain order types), and managing net exposure limits so that no single market move creates catastrophic book losses.
The regulatory context: B-book operations are legal in most jurisdictions and constitute the primary model for many of the largest retail brokers globally. However, some jurisdictions restrict or require disclosure of B-book practices. Aspiring operators should confirm the regulatory requirements for their target jurisdiction before defaulting to a B-book model.
Hybrid: The Risk-Managed Middle Ground
Most established brokerages run a hybrid model — routing some clients and some trade types A-book, and internalizing others B-book, based on defined risk rules.
The logic is straightforward:
- New retail clients with no track record go B-book initially. Revenue is generated from the natural distribution of wins and losses in that segment.
- Clients showing consistent profitability over a defined period trigger an automatic reclassification. Their flow routes to A-book, where the broker earns spread mark-up without carrying the risk of paying their winnings.
- Large single positions above a defined notional threshold route to A-book regardless of client classification, to prevent any single trade from creating dangerous book exposure.
Hybrid models maximize revenue capture from the natural retail loss distribution while protecting the book from skilled flow. The risk management system — not the broker manually — makes routing decisions in real time based on client segmentation rules.
The operational requirement: Hybrid execution requires a technology layer that can classify clients, apply routing rules, and execute those decisions faster than the trade arrives at the LP. For brokers building from scratch, this is significant infrastructure. For brokers using an integrated BaaS platform with pre-built risk routing, it is a configuration decision — not a build project.
What New Operators Actually Need to Decide
If you are launching your first brokerage, the choice between A-book, B-book, and hybrid comes down to three variables:
Your target client base. Trading communities, IB networks, and social trading groups skew retail. Retail-heavy client bases with shorter trading histories are better suited to a B-book or hybrid start.
Your LP access and volume. If you cannot access institutional LP pricing at launch, A-book margins are thin. B-book or hybrid start, with a plan to migrate profitable-client flow to A-book as volume scales, is the more common path.
Your risk tolerance and capital buffer. B-book requires capital reserves sufficient to pay winning client withdrawals before the natural loss distribution covers them. An undercapitalized B-book that runs out of reserves before the month ends is an operational crisis.
For most operators launching through a white-label BaaS platform, the practical path is:
- Launch with a hybrid configuration — B-book on the retail majority, A-book routing rules pre-built for outlier flows.
- Let the risk monitoring layer classify clients automatically as the book matures.
- Adjust routing thresholds quarterly as you understand your client distribution.
The ProtonX Approach: Execution Infrastructure Without the Build
ProtonX provides a fully integrated execution infrastructure — LP connection, price engine, bridge, and risk routing — as part of the BaaS platform. Operators do not select a single execution model and build around it. They launch with a hybrid-capable infrastructure that routes traffic based on pre-configured risk rules from day one.
The financial reality: ProtonX pricing is $2,500 to set up and $2,500 per month. A brokerage generating 5,000 lots per month at a $10 gross mark-up per lot earns $50,000 monthly in gross spread revenue. Platform cost is $2,500, leaving $47,500 gross before other operational expenses. Break-even at that volume requires approximately 250 lots per month — a realistic target for a trading community with an established following launching in the first 30 days.
The platform includes Tier-1 LP access pre-integrated, which means operators access institutional-grade pricing from launch without meeting standalone LP volume minimums. The risk routing layer handles A-book/B-book decision logic automatically, without requiring the operator to build or configure a separate risk management system.
Launch timeline is 7 days. Licensing is not required to operate under ProtonX’s framework, removing the most common pre-launch blocker for first-time operators.
Execution model is not a permanent commitment. As your brokerage scales and your client book matures, routing rules adjust. ProtonX’s infrastructure supports that progression without requiring a platform migration.
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Conclusion
A-book, B-book, and hybrid are not just terminology. They determine your revenue model, your risk exposure, and your regulatory posture. Most operators who launch without thinking through their execution model find out its implications the hard way — either through thin A-book margins on insufficient volume, or through B-book losses from unmanaged skilled-trader flow.
The good news: you do not have to build the routing infrastructure yourself, and you do not have to choose one model and commit permanently. A hybrid-capable platform lets you launch with sensible defaults and evolve your configuration as your book matures.
The execution model question answers itself once your client base takes shape.
FAQ
What is the difference between A-book and B-book in forex?
In an A-book model, the broker routes client trades directly to a liquidity provider. The broker earns a spread mark-up and carries no market risk. In a B-book model, the broker acts as the counterparty, internalizing client trades. The broker profits when clients lose and pays when clients win.
Is B-book execution legal?
Yes. B-book execution is legal in most forex jurisdictions and is the primary model used by many large retail brokers globally. Some jurisdictions require disclosure or place restrictions on certain B-book practices. Operators should confirm requirements for their target regulatory environment before launch.
What is a hybrid execution model?
A hybrid model routes different client segments or trade types to different execution paths. Retail clients with no established track record may trade on B-book; consistently profitable clients automatically route to A-book. Large individual positions often route A-book regardless of client classification to cap single-trade book exposure.
Do I need a lot of capital to run a B-book brokerage?
A B-book requires a capital reserve sufficient to cover client withdrawals before the natural distribution of client losses generates operating revenue. The required reserve depends on client volume and withdrawal frequency. Undercapitalized B-book operations are a common failure point for first-time operators.
Can I switch execution models after launch?
Yes. Most modern brokerage platforms allow routing rules to be adjusted without a platform migration. Many operators launch with hybrid defaults and refine their A-book/B-book thresholds as their client book matures.
Does ProtonX offer A-book, B-book, or hybrid execution?
ProtonX’s platform supports hybrid execution — with pre-integrated Tier-1 LP access for A-book routing and B-book internalization for retail flow, managed through automated risk routing rules. Operators do not need to build separate systems for each execution path.
What volume do I need to access institutional LP pricing?
Most standalone prime-of-prime LPs require minimum monthly volumes that a new brokerage typically cannot meet at launch. ProtonX’s pre-integrated LP access removes that threshold for operators on the platform, providing institutional-grade pricing from the first trade.