Internalisation Means Your Order Never Reaches an Exchange
A large share of retail orders are filled by wholesale market makers rather than sent to a public venue. The client usually gets a better price and the public quote gets less information.
What Happens to a Retail Order
A retail investor submits an order and assumes it goes to an exchange. Frequently it does not.
The broker routes it to a wholesale market maker, which fills it from its own inventory, generally at a price slightly better than the best public quote.
The trade is reported afterwards but was never exposed to the public order book.
The client typically gets a fractionally better price than the public quote. What the public market loses is the chance to interact with that order at all.
Why Wholesalers Want the Flow
Retail orders are attractive because they are, on average, uninformed.
A market maker facing an institutional order worries that the institution knows something. A market maker facing a retail order buying 100 shares has far less concern about adverse selection.
Being able to identify and fill only the uninformed portion of order flow is enormously valuable. It allows quoting inside the public spread while earning a reliable margin, because the flow is not systematically correct about short term direction.
The Segmentation Argument
| Position | Argument |
|---|---|
| In favour | Retail gets better prices than the public quote |
| In favour | Competition among wholesalers passes value on |
| Against | Public quotes widen without uninformed flow |
| Against | Price improvement is measured against a quote that internalisation itself worsened |
The second objection is the sharpest one. If removing uninformed flow from public venues causes public spreads to widen, then price improvement measured against that widened quote overstates the benefit.
Whether that effect is large is genuinely disputed, and the counterfactual is difficult to establish because you cannot observe the market that would exist without internalisation.
The Connection to Order Flow Payments
Wholesalers frequently pay brokers for the right to receive this flow. That payment is what funds commission free trading at many retail brokers.
The arrangement is coherent: the flow has value because it is uninformed, wholesalers pay for it, and the payment subsidises the client trading costs.
The objection is that the client is not told the arrangement in a way they understand, and that the broker routing decision is influenced by payment rather than solely by execution quality. Several jurisdictions have banned the practice on those grounds.
Where It Matters More
In highly liquid securities, internalisation has limited effect on price formation, since plenty of other activity establishes the price.
In less liquid securities, removing a meaningful share of order flow from public venues has a larger proportional effect, and the public quote becomes less informative because less of the actual trading interest passes through it.
The Broader Pattern
Internalisation, dark pools, and single dealer platforms all do a version of the same thing: execute away from the public book.
Each has a defensible rationale for the participant using it. The aggregate concern is that if enough activity moves off the public venues, the price those venues produce, which everything else references including the internalised trades themselves, is formed by a shrinking proportion of actual interest.
That is the structural question and it does not have a settled answer.
The Bottom Line
Internalisation fills retail orders against a wholesaler inventory rather than on a public venue, usually at a fractionally better price. It works because retail flow is uninformed and therefore safe to trade against. The unresolved objection is that the public quote used to measure the improvement is itself degraded by the removal of that flow, and nobody can observe the market that would exist otherwise.