# Level 2

Also written depth of book.

*https://stockmarketstack.com/glossary/level-2 · next to Stock Market Data APIs*

**Definition:** The resting orders behind the best bid and offer, bought from each venue as its own product on its own licence. Level 1 is the top of the book plus the trade stream; Level 2 is what sits underneath it. The consolidated tape carries no depth, so there is no national Level 2 to buy, and what a broker labels Level 2 is usually one venue's book.

## How it works

An order book is the set of resting limit orders in one instrument at one venue: buy orders ranked
down from the highest price, sell orders ranked up from the lowest. The best of each side is the top
of the book. Market depth is everything behind that top — how much size is waiting, and at what
distance from the touch.

Level 1 is the top of the book and the trades. Level 2 is the layer underneath, and it is a different
product, bought per venue, licensed per venue, because each venue only knows its own resting orders.

Depth arrives in two shapes, and the difference decides what you can compute.

**Aggregated by price.** One row per price level, with the sizes at that price summed. This is the
ladder in a trading platform. It answers "how much is offered at 10.02" and nothing about who or in
what order.

**Market by order.** Every resting order carried separately, with a reference number you can follow
through modification, execution or cancellation. This is what queue-position and order-lifecycle work
needs, and it is several times the message volume of the aggregated view.

## The trap in the name

At Nasdaq, the product actually called Level 2 is neither of those. Its own specification, Nasdaq
Level 2 version 2.0, describes the feed as carrying "Top-of-File Quotations": for registered Nasdaq
market participants, a top-of-file position based on attributed orders and quotations entered by the
firm, and the feed "will provide only the best bid and ask position for each Nasdaq market participant
registered in an issue". Unattributed orders in the Nasdaq system appear only as a top buy and sell
price under the MPID NSDQ. The specification then says plainly that for greater depth information you
should refer to the Nasdaq TotalView Aggregated or TotalView ITCH products.

So the historical Level 2 is a per-participant view — one line per market maker — rather than a
price ladder or a full book. Twenty market participants each showing their best quote is not twenty
price levels, and it is not the whole of the venue's resting interest either. "Level 2" as sold by a
retail broker is looser still: it may be one venue's book, a subset of venues the broker happens to
license, or a vendor's own aggregation, at whatever number of levels the licence covers.

## Why there is no consolidated Level 2

The [consolidated tape](https://stockmarketstack.com/glossary/consolidated-tape) was built to carry the best bid, the best offer
and the trades, and not depth. The SEC's Market Data Infrastructure Rule set out to change that, and
it has not yet: in an order dated 15 January 2026 the Commission granted the plan participants
temporary exemptive relief from the odd-lot depth requirement of Rule 600(b)(69)(ii) until the first
business day of May 2028.

Until then, there is no national depth product. That is the structural reason depth costs what it
does — you buy it venue by venue, and the fee is per venue per user. Nasdaq's US equities price list
puts TotalView at 15 dollars a month for a single non-professional user and several times that for a
professional, per venue, before any non-display or redistribution line.

## Why it matters here

Two things follow for cards on this site.

First, a card that says "Level 2" is making a weaker claim than it sounds. Ask which venues, which
shape — price levels or individual orders — and how many levels deep.
[Bookmap](https://stockmarketstack.com/tools/bookmap), [ATAS](https://stockmarketstack.com/tools/atas) and [ExoCharts](https://stockmarketstack.com/tools/exocharts) are built to
visualise depth and are only as good as the feed under them;
[Databento](https://stockmarketstack.com/tools/databento) and [AlgoSeek](https://stockmarketstack.com/tools/algoseek) sell the feeds and the history, and
name the venue.

Second, depth is where [tick data](https://stockmarketstack.com/glossary/tick-data) volumes stop being manageable, and the
[fee stack](https://stockmarketstack.com/guides/real-time-market-data-fees) applies per venue rather than once. A program reading
a depth feed is also [non-display use](https://stockmarketstack.com/glossary/non-display-use), which is priced per firm.

The number the rest of the market treats as the price is still the [NBBO](https://stockmarketstack.com/glossary/nbbo), which is
one bid and one offer with nothing behind it. Depth is the thing the NBBO deliberately does not tell
you, and it is sold accordingly.

## Where you will meet this

- [Bookmap](https://stockmarketstack.com/tools/bookmap.md)
- [ATAS](https://stockmarketstack.com/tools/atas.md)
- [Exocharts](https://stockmarketstack.com/tools/exocharts.md)
- [Databento](https://stockmarketstack.com/tools/databento.md)
- [AlgoSeek](https://stockmarketstack.com/tools/algoseek.md)
- [HedgeFollow](https://stockmarketstack.com/tools/hedgefollow.md)
- [OneTick](https://stockmarketstack.com/tools/onetick.md)
- [Tick Data](https://stockmarketstack.com/tools/tickdata.md)

## FAQ

### Is Level 2 the same thing as the full order book?

Not necessarily, and at Nasdaq specifically it is not. The product called Nasdaq Level 2 carries the best bid and ask position for each registered market participant in an issue, and its own specification points you at the TotalView products for greater depth. Ask how many price levels a feed carries and whether every resting order is in it.

### Why does my broker's Level 2 window disagree with another broker's?

Because each is showing a book, not the book. Depth is sold per venue, every venue has a different set of resting orders, and there is no consolidated depth product to reconcile them against. Two windows fed by two different exchanges, or by different subsets of exchanges, will show different sizes at the same price and both be correct.

## Sources

1. [Nasdaq Level 2, Version 2.0](https://www.nasdaqtrader.com/content/technicalsupport/specifications/dataproducts/Level2Specification.pdf) — The Nasdaq Stock Market, LLC, read 2026-09-21
2. [Nasdaq US Equities Price List, rates effective 2025, 2026 and 2027](https://www.nasdaqtrader.com/content/ProductsServices/PriceList/Nasdaq_US_Equities_Price_List_2025_2026_2027.pdf) — Nasdaq, 2025-01-08
3. [Order Granting Temporary Exemptive Relief from Rule 600(b)(69)(ii) of Regulation NMS, Release No. 34-104612](https://www.sec.gov/files/rules/exorders/2026/34-104612.pdf) — US Securities and Exchange Commission, 2026-01-15

*Last updated 2026-09-21. A reference page, corrected in place — not a dated post.*