Dark PoolATS
A dark pool is a private trading venue that does not show orders before they trade. Institutions use dark pools to buy or sell large blocks without revealing their intentions; trades are reported after execution.
A dark pool is a private trading venue that does not show its orders to the public before they trade. Large investors use dark pools to buy or sell big blocks without signalling their intentions to the rest of the market.
- Category
- Market Structure
- Reading time
- 3 min
- Also called
- Dark pool of liquidity, Non-displayed venue
- Updated
A dark pool in plain words
A dark pool is an alternative trading system that doesn't show its quotes to the public.1
Users can place orders without revealing their size or price to anyone else in the pool.2
An ATS is not a stock exchange — it is a different kind of venue with its own rules.2
How a dark pool trade works
Send an order
An institution sends a large order to the ATS.
Stay hidden
The venue does not display quotations to the public.1
Match
The order meets a counter-order, often at a price tied to the public quote.
Report
The completed trade is reported afterwards.
Limit impact
Hiding size reduces market impact.
Weigh the trade-off
Keep the bigger debate in mind: regulators ask whether so much hidden trading harms public price discovery.3
Worked examples
Example 1 — Block sale
Saved 100,000A fund sells 400,000 hypothetical shares. On a lit book it estimates a 0.30 drop; in the dark pool, 0.05.
| Lit impact | −120,000 |
| Dark impact | −20,000 |
| Impact saved | 100,000 |
Because orders are placed without publicly displaying the size and price, impact is smaller.2
Example 2 — No match
No fillA hypothetical order rests unfilled all day.
| Filled | 0 |
Because nothing is displayed, the pool can't advertise for the other side, so a fill is never guaranteed.1
Example 3 — Retail view
Seen only afterA trader sees a large print appear after the fact.
| Pre-trade info | None |
Regulators have worried that hidden trading could create a two-tier market in which the public sees less of the real prices and liquidity.1
Dark pool vs exchange
| Aspect | Dark pool | Exchange |
|---|---|---|
| Quotes shown | No | Yes |
| Legal status | ATS | National securities exchange |
| Users | Mainly institutions | Everyone |
| Impact | Lower for blocks | Higher for blocks |
Where dark pools matter
Large orders
Lower impact than the lit Order Book.
Order flow
Reading prints in Order Flow analysis.
Volume
Off-exchange share of Volume.
Execution
Part of Slippage control for funds.
Advantages and disadvantages
Advantages
- Reduce market impact on big trades.
- Hide trading intent.
- Can trade at or inside the public spread.
Disadvantages
- No pre-trade transparency.
- Fills are uncertain.
- May weaken public price discovery.
- Retail traders see trades only afterwards.
Going deeper
Read as far as you need. Each level builds on the one before it.
Definition
Beginner
Technically, a dark pool is an ATS that keeps its quotes hidden.1
Venue terms
Intermediate
They sit outside the main exchanges, and their orders never appear in the public order book.4
Policy debate
Advanced
The open question is whether hidden volume has grown big enough to weaken public price discovery.3 Rules differ by country.
Common mistakes
Thinking dark pools are illegal
They are regulated venues.
Reading every print as bullish
Direction is often unknown.
Ignoring delays
Reports come after the trade.
Assuming same rules worldwide
Rules differ by country.
Check your understanding
Test yourself before moving on. Each answer comes with an explanation.
Key points to remember
- Dark pools hide orders before trading.
- In the US they are ATSs, not exchanges.
- They reduce impact for big trades.
- They may reduce public price discovery.
- Rules differ by country.
Frequently asked questions
Can retail traders use dark pools?
Are dark pools legal?
Do dark pool trades show up?
Further learning
- Order Book
The lit alternative.
- Order Flow
Reading trades.
- Liquidity
Why size matters.
- Volume-Weighted Average Price
Benchmark for big orders.
Sources
This article is written in our own words. The sources below support the specific facts, rules and figures marked with a number in the text. Links open the original publisher’s page.
- U.S. SEC. Fact Sheet: Strengthening the Regulation of Dark Pools (opens in a new tab) Checked .
- U.S. SEC (Investor.gov). Alternative Trading Systems (ATSs) (opens in a new tab) Checked .
- U.S. SEC. SEC Issues Concept Release Seeking Comment on Structure of Equity Markets (opens in a new tab) Checked .
- Bookmap. Glossary – Bookmap Knowledge Base (opens in a new tab) Checked .
Educational content, not financial advice. Examples use hypothetical prices and simplified costs; actual fees, margin rules and regulations vary by broker, market and country. We are not affiliated with any publisher linked above. Last reviewed . Report an error or request a source credit.