ECN vs Market Maker vs STP: How Broker Execution Models Actually Work

ECN, STP and market maker are the three labels every broker fights over and the three that most retail traders misunderstand. The marketing version says ECN good, market maker bad, STP somewhere in between. The desk version is that these are descriptions of plumbing and incentives, almost every real broker is a hybrid of all three, and the label on the homepage tells you far less than the execution disclosure and the all-in cost. This guide is how the models actually work, where the conflict of interest is real and where it is overstated, and how to compare brokers on what matters instead of the badge.

The model name is a marketing decision. Your fill quality and your total cost are facts. Trade on the facts.

By Ken Chigbo, Founder, KenMacro. 18-plus years in markets, London trading floor and institutional FX. The desk pressure-tests broker execution inside the MACRO MASTERY desk.

The market maker, or dealing-desk, model

A market maker quotes its own bid and offer and is willing to be your counterparty. When you buy, it can sell to you from its own book rather than sourcing the other side externally. That is not inherently sinister. It is what every bank FX desk and every exchange specialist has always done, and it is the reason a market maker can show a tight, stable price and fill you instantly even when external liquidity is thin, for example in a fast tape or an off-hours session.

The model does create a structural conflict. If the broker warehouses your losing trade rather than hedging it, your loss is its gain. That is the kernel of truth behind the retail fear. The honest framing is that a regulated, well capitalised market maker manages this with internal netting, risk limits, external hedging of net exposure and a best-execution obligation, and that warehousing is a normal risk-management activity, not by itself misconduct. The problem is not the model. The problem is a poorly capitalised or weakly regulated firm whose execution quality conveniently degrades when it is carrying risk against you.

A-book, B-book, and why almost everyone is hybrid

A-book means the broker passes your order to an external liquidity provider and earns the spread or commission on the flow, with no direct exposure to whether you win or lose. B-book means the broker keeps the position internally and takes the other side, so it is directly exposed to your profit and loss. Retail coverage treats this as a moral binary: A-book honest, B-book predatory.

The reality is that almost no real broker is purely one or the other. Most run a hybrid. Flow that nets off internally costs nothing to keep. Flow from clients who are, on aggregate, unprofitable can be retained within risk limits. Flow that is too large or too sharp is hedged or routed out. The same client can be handled differently over time as the broker’s book and risk appetite change. Hybrid routing is the industry standard and is not, by itself, evidence of anything wrong. The question that matters is not whether a given order was internalised. It is whether your execution quality, fills, slippage and pricing, stays consistent regardless of how the broker chose to handle it.

STP: what it does and does not guarantee

Straight-through processing means an order is routed to one or more external liquidity providers without a manual dealing desk intervening on that order. That is a real and meaningful property. It removes the human discretion that, at a badly run firm, can become re-quotes and asymmetric slippage on the routed flow.

What STP does not do is guarantee good pricing or the absence of a conflict. STP describes routing, not incentives. An STP broker still chooses its liquidity providers, can mark up the spread it receives before showing it to you, can sit behind a provider that applies last look, and can run an STP-branded account while the wider group B-books other flow. STP is a useful fact about how a particular order travels. It is not a regulated guarantee of best execution, and treating the three letters as a clean bill of health is exactly the mistake the marketing wants you to make.

ECN: the pool, the economics, and the marketing

An ECN is a shared electronic pool where orders from many participants, banks and non-bank market makers and other clients, meet and match. The defining commercial feature for retail is the pricing structure: a raw or near-raw spread that reflects the underlying pool, plus an explicit per-lot commission. You see a tighter quoted spread and pay a visible fee, instead of a wider all-in spread with the cost buried inside it.

What genuinely matters about a real ECN-style setup is depth of book, the quality and number of liquidity providers, how slippage is applied, and whether the raw spread holds up under stress or blows out the moment volatility arrives. What does not matter is the word ECN on the account page. ECN is one of the most marketed labels in the industry and is routinely applied to setups that are really marked-up STP or hybrid. Treat the badge as a claim to be verified by the execution disclosure and the measured cost, not as a fact.

The conflict of interest, sized honestly

The conflict is real on internalised flow and it is worth understanding rather than catastrophising. A market maker or hybrid broker carrying the other side of your position has, in the narrow sense, an interest in that position losing. That is true and should not be hand-waved away. It is also bounded. A credibly regulated broker operates under best-execution rules, client-money segregation and capital requirements, and most serious firms net and hedge rather than betting the house against retail. The conflict is most dangerous not in its existence but in its symptoms: execution that degrades selectively, slippage that is consistently worse in the client’s losing direction, re-quotes that appear only when the trade is going your way. Those are measurable. The conflict is overstated when it is treated as proof that every market maker is rigged, and understated when traders ignore slippage asymmetry because the broker has a nice ECN badge.

How to compare true cost instead of the label

The only honest comparison is all-in cost at your size and your times. Build it the way a desk would:

• Spread: the spread you are actually filled at, sampled at the sessions and around the events you actually trade, not the marketing best-case figure.
• Commission: the explicit per-lot fee on raw-spread accounts, converted into the same units as the spread so the two are directly comparable.
• Swap or financing: the overnight cost, which dominates total cost for anything held more than intraday and is ignored by almost every comparison page.
• Slippage symmetry: whether positive slippage is passed to you as readily as negative slippage is taken, observed over many fills, not assumed.

A tight raw spread plus commission can total more than a wider marked-up spread once it blows out under news. The reverse is just as common. The model name does not tell you which. Only the summed, measured cost does.

Related reading

• Forex trading costs explained (the spread, commission and swap maths in full)
• How to choose a forex broker (the full selection checklist this fits into)
• Forex broker regulation explained (the regulated entity is the real guarantee, not the label)
• The free macro framework (the regime read your execution costs feed into)

Frequently asked questions

What is the difference between ECN, STP and market maker?

A market maker can take the other side of your trade on its own book. STP routes your order to external liquidity providers with no dealing desk on that order. ECN matches orders inside a shared liquidity pool, usually raw spread plus commission. The labels overlap, almost every real broker is a hybrid, and the execution disclosure and all-in cost tell you more than the model name.

Is a market maker broker a scam?

No. Market making is a legitimate, regulated model and a well-run market maker can give tight, stable pricing and instant fills. It carries a structural conflict because the broker can gain when warehoused flow loses, but regulation, capital rules and hedging manage that at serious firms. The model is fine when the broker is sound and execution holds up under stress.

What is A-book versus B-book?

A-book passes your order to an external liquidity provider; the broker earns spread or commission and has no direct exposure to your result. B-book keeps the position internally so the broker takes the other side. Almost no broker is purely one or the other. Hybrid routing is the industry norm and not a red flag by itself.

Does STP remove the conflict of interest?

No. STP describes routing, not pricing or incentives. An STP broker still picks its liquidity providers, can mark up the spread, can sit behind last look and can B-book other flow in the group. STP removes a manual dealing desk on the routed order, which matters, but it is not a guarantee of best execution. Read the disclosure, not the label.

Is an ECN broker always cheaper?

No. ECN is usually raw spread plus explicit commission; a market maker is often a wider all-in spread. The fair comparison is total cost: filled spread plus commission plus swap, at your size and your times. A raw spread that blows out under news plus commission can cost more than a stable marked-up spread, and the reverse is also common.

When is a market maker model fine for me?

When the broker is well capitalised and credibly regulated, the all-in cost is competitive at your size and style, fills are reliable and slippage is roughly symmetric, and execution does not degrade around news. For many lower-frequency traders a sound market maker is adequate and sometimes cheaper. Judge on measured execution and regulation, not the model name.

Educational analysis only, not financial advice. Past performance does not guarantee future results. Always manage risk and never risk more than you can afford to lose. This is macro education and scenario framework, never a signal or a recommendation to trade.