A-Book vs B-Book vs Hybrid Brokerage
A-book, B-book and hybrid describe what happens to a client order after it reaches you. The choice shapes your revenue, your risk, your capital needs and your technology. Most established brokers run a hybrid model with explicit rules; the important thing is that the rules are deliberate, documented and consistent with what you tell clients and your regulator.
A-book: pass the risk through
Every client order is hedged with a liquidity provider, so you have no market exposure. Revenue comes from spread markup and commission. It is the lowest-variance model and the easiest to explain to regulators and partners, but margins are thinner and you are exposed to your provider's execution quality and credit terms.
B-book: retain the risk internally
Orders are filled in-house and exposure sits on your book. Revenue includes the profit and loss of that book, which is why it can be far more profitable — and far more volatile. It demands genuine risk management, capital to absorb drawdowns, clear governance and careful conflict-of-interest disclosure.
Hybrid: route by rule
Flow is classified and routed accordingly: consistently profitable, high-volume or latency-sensitive clients are hedged externally, while smaller retail flow that naturally offsets is retained within limits. This is the industry norm because it balances margin and risk, but it only works if classification is rule-based rather than discretionary and after the fact.
The infrastructure each model needs
A-book needs solid connectivity and a bridge. B-book needs real-time exposure monitoring, per-symbol and per-client limits, and stress testing. Hybrid needs all of that plus a routing engine that can classify accounts and move them between books automatically, with a full audit trail.
Regulatory and disclosure considerations
Regulators care that your execution policy is accurate, that conflicts of interest are disclosed, and that you can evidence best execution. Your client agreement and website should describe how orders are handled, and your actual routing configuration should match that description exactly.
How to choose at launch
New brokers with limited capital and no risk team should start close to fully A-book, prove the acquisition and retention engine, then introduce internalisation gradually with hard limits once monitoring, governance and capital are in place. Starting with an aggressive internal book and no risk infrastructure is how brokers lose their first year of profit in a single volatile session.
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Frequently asked questions
Is B-book execution allowed?
Internalising risk is a legitimate, widely used model in most jurisdictions, provided you meet capital requirements, manage conflicts of interest and disclose your execution approach accurately.
Which model do most brokers use?
Hybrid. Flow is classified and routed by rule, with some hedged externally and some retained internally within defined risk limits.
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