What Level 2 Market Data Actually Is, and What It Costs

Level 2 is one of the few pieces of market plumbing that retail traders pay for by name. It appears on platform pricing pages as an add-on, and the assumption underneath the purchase is that it buys the order book.

It buys something narrower than that, defined by the exchange that sells it. The gap between the name and the product is where most of the confusion about this data lives.

Level 2 Is a Product Name, Not a Description of the Book

The phrase entered retail vocabulary through vendor menus rather than through market structure. An exchange packaged a tier of its quote data, gave it a number, and sold it. The number stuck.

That origin matters because a product name carries a specification, and a description does not. When a platform offers Level 2, it is offering a named feed with defined contents, on terms the exchange sets.

Most explanations of the subject treat the term as a synonym for the order book, market depth and the tape, moving between the four as though they name one thing. They name different things, and only one of them is a product you can buy.

The practical consequence is that two brokers can both advertise Level 2 on the same security and deliver the same contents, because neither of them defines it. The exchange does. What varies between brokers is the display, the latency of the path and the fee they pass on.

This is worth establishing before any question about how to read the ladder, because the answer to what the ladder can tell you depends entirely on what was in the feed. Traders coming to this from equities generally meet it first as a line item on a platform bill, alongside the other costs covered in our guide to online stock trading.

What the Feed Aggregates, and What It Leaves Out

A quote feed has to make a choice about granularity, and the choice is the whole substance of the product tiers.

The narrowest choice publishes one price on each side: the best bid and the best offer, with a size. Nothing below the top of the book appears at all.

The Level 2 choice publishes more than one line per side, organised by market participant. Each participating firm or venue contributes its own quotation, so the ladder shows several prices with an identifier beside each.

The widest choice publishes the book itself, every displayed order at every price level, without aggregating them into one line per participant. That is a materially larger volume of data and a separate product.

The distinction that gets lost is between a price-aggregated view and an order-by-order view. A single line in a participant-level feed can represent one order or many, and the feed does not say which. Reading a large size at a level as a single committed order is an inference the data does not support.

It also leaves out anything not displayed. Orders held without publication, and interest resting away from the displayed venues, are absent by construction. The ladder is a picture of what was published, which is not the same as a picture of what exists.

The Exchange Sells More Than One Depth Product

The clearest evidence that Level 2 is not the book is that the exchange selling Level 2 also sells something deeper, and says so plainly in its own product documentation.

Nasdaq markets TotalView as its full depth-of-book feed and positions it directly against Level 2 in its own materials, stating that TotalView carries more than twenty times the liquidity of Level 2. That figure is the claim of Nasdaq about its own products, published on its product pages, and it is cited here as such rather than as an independent measurement.

Whatever weight is given to the multiple, the structural point is not in dispute and comes from the seller: two products, two depths, two prices. If Level 2 were the order book there would be nothing left for a deeper product to contain.

This also explains a common experience. A trader buys Level 2, watches the ladder, and finds that size appears and disappears in ways the display does not account for. Part of that is orders being amended and withdrawn in the normal course. Part of it is simply that the feed being watched was never the whole book, and the missing portion was on sale separately the entire time.

Platforms that present a depth ladder do not always make the tier explicit in the interface, which is one of the things worth checking in the data documentation of any platform, including cTrader.

Who Sets the Price of the Data, and Why It Is Not Your Broker

Market data on a US equity exchange is not priced by the broker who bills you for it. It is priced by the exchange, and the exchange is a self-regulatory organisation whose fees pass through a public process.

A self-regulatory organisation that wants to change a fee cannot simply change it. The revision goes to the Securities and Exchange Commission as a proposed rule change under Exchange Act Section 19(b), where it is published, opened to comment and considered before it can take effect. Regulation NMS treats that filing route as the mechanism through which market data charges are reviewed.

Two things follow for anyone reading a platform bill. The first is that the underlying rate is not a matter the broker negotiates with the customer, so shopping between brokers changes the markup and the packaging rather than the exchange fee itself. The second is that the rate is a matter of public record by design.

A note on what could not be verified for this page. The current rate schedules were sought at the trader-facing site of the exchange, and every product page requested there returned an identical generic shell rather than the schedule, so no dollar figure is quoted here. Where a specific rate matters, the filed fee schedule is the document to read, and it is public.

Charting services that resell exchange data are subject to the same structure, which is why depth data is usually a separately priced tier rather than part of a base plan, as it is on TradingView.

Depth-of-Book Quotes Have No Trade-Through Protection

This is the part of the subject that changes what the data can honestly promise, and it is absent from the general explanations of Level 2 entirely.

Regulation NMS contains an Order Protection Rule. It exists to stop an execution happening at a worse price than a protected quotation being shown at another trading center at that moment. The scope of that protection is deliberately narrow: it attaches to the best bid and the best offer of each trading center, provided the quotation is automated and immediately accessible.

Everything below the top of the book falls outside it. Depth-of-book protection was argued for while Regulation NMS was being adopted and was not adopted. The prices sitting two, five and ten lines down a Level 2 ladder are displayed, and they are real quotations, but no rule requires an order to respect them.

The consequence is specific. The ladder can show an apparently attractive price several levels down at a particular venue, and an order routed elsewhere may execute without any obligation to reach it. What the regulation guarantees concerns the top line, and the depth is information rather than protection.

There is a related timing rule worth knowing about, because it constrains how the data reaches a subscriber. Adopted Rule 603(a) bars an exchange or a broker-dealer from releasing its own data to any vendor or customer ahead of the moment it hands the same data to the network processor that builds the consolidated quote. A separately sold depth feed therefore cannot lawfully reach a subscriber earlier than the consolidated one does.

Level 1, Level 2 and Full Depth Side by Side

The three tiers differ along four axes at once: how many lines per side, how those lines are grouped, whether the individual order survives the aggregation, and what the data is protected against.

Why a Retail Forex or CFD Account Never Carries It

The question of Level 2 for currencies comes up constantly, and the answer is structural rather than commercial.

Level 2 is an exchange product. It exists because an exchange operates a central book, records what is displayed on it, and is in a position to license that record. Spot foreign exchange has no such central book, so there is nothing to license and no feed to sell.

A contract for difference adds a second layer. The position is with the provider rather than on a market, so even where the underlying trades on an exchange, the account is not a subscriber to that market.

What platforms do offer on these instruments is a depth window built from a different source, and the distinction between the two is developed in full in our guide to depth of market in forex. That page also covers how to read such a window and why inferring barriers from displayed size fails, so those questions are not repeated here.

The short version for this page is that a depth ladder appearing on a currency pair is not Level 2 in the sense used above. Applying conclusions drawn from equity depth to it imports assumptions that the source does not support.

Who This Data Is Not For

Depth data is usually presented as an upgrade, which frames the decision as whether to progress rather than whether to subscribe. Framed properly, several groups are paying for something they cannot use.

Anyone holding positions for days or longer is one. A ladder describes displayed interest in the current moment, and that moment has no bearing on an outcome measured over weeks.

Anyone trading only instruments without a central book is another, for the reason set out above. The subscription cannot deliver what the instrument does not have.

Anyone whose orders are small relative to the size at the top of the book is a third. If a position fills at the first line every time, the lines below it are not information about that trade.

The group it does serve is narrow and identifiable: traders sending orders large enough to consume more than the top line, on exchange-traded instruments, over horizons short enough for displayed interest to still be there on arrival.

Frequently Asked Questions