Smart Order RoutingSOR
Smart order routing is software that decides where to send an order — or how to split it across venues — to get the best available price and fill, taking into account quotes, fees and depth.
Smart order routing is software that decides where to send an order, or how to split it across venues, to get the best price and fill. It looks at quotes, fees and depth. It is widely used by brokers and institutions.
- Category
- Market Structure
- Reading time
- 3 min
- Also called
- Smart router, SmartRouting
- Updated
Smart order routing in plain words
A smart order router scans exchanges and dark pools to find the best prices on offer for stocks, options and multi-leg orders.1
Smart routing has been widespread among brokers since at least the mid-2000s.2
Manual handling of big institutional orders is now rare; algorithms and smart routers do most of the work.3
How a smart order router works
Receive order
The broker gets your order.
Scan venues
It checks quotes across exchanges and dark pools.
Compare costs
It weighs price, fees and depth.
Split if needed
Large orders are divided into child orders.
Re-route
Let the router keep re-checking conditions and redirect all or part of the order to get it filled fast.1
Review results
Remember results depend on how the router and algorithms are set up.4
Worked examples
Example 1 — Split buy
≈ 15.0056Hypothetical buy 900: Venue A 400 @ 15.00, Venue B 500 @ 15.01.
| Average | (6,000 + 7,505) ÷ 900 ≈ 15.0056 |
The router took the best prices across venues first.1
Example 2 — Fees matter
Venue BVenue A 15.00 + fee 0.003; Venue B 15.001 + no fee.
| Net A | 15.003 |
| Net B | 15.001 |
The router weighed fees as well as price — and how it's configured changes the outcome.4
Example 3 — Quote fades
AdaptedVenue A's quote disappears mid-order.
| Action | Re-route |
When the market moved, the router redirected the remaining shares to fill them quickly.1
Smart vs direct routing
| Aspect | Smart routing | Direct routing |
|---|---|---|
| Venue choice | Automatic | Trader picks |
| Speed | Fast, adaptive | Depends on trader |
| Control | Less | More |
| Best for | Most orders | Special strategies |
Where SOR matters
Execution
Reducing Slippage.
Brokers
How a Broker routes.
Costs
Avoiding high Trading Fees and Commissions.
Depth
Using Liquidity across venues.
Advantages and disadvantages
Advantages
- Finds better prices across venues.
- Adapts to changing quotes.
- Supports best execution.
Disadvantages
- Logic is often opaque.
- Calibration affects outcomes.
- May route for broker benefit.
- Can leak information on large orders.
Going deeper
Read as far as you need. Each level builds on the one before it.
Purpose
Beginner
Routers scan many venues, including dark pools, for the best available prices.1
Prevalence
Intermediate
Algorithms and smart routers have largely replaced manual order handling for institutions.3
EU view
Advanced
Because outcomes depend on how routers are configured, their settings matter for best execution.4
Common mistakes
Assuming routing is neutral
Check incentives.
Ignoring fees
Net price matters.
Not reviewing reports
Check execution quality.
Overriding without reason
Direct routing can cost more.
Check your understanding
Test yourself before moving on. Each answer comes with an explanation.
Key points to remember
- SOR picks venues automatically.
- It weighs price, fees and depth.
- It can split and re-route orders.
- Calibration changes outcomes.
- Widely used by brokers.
Frequently asked questions
Do retail brokers use SOR?
Can I choose a venue?
Does SOR guarantee best price?
Further learning
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.
- Interactive Brokers. IB SmartRouting (opens in a new tab) Checked .
- U.S. SEC. Regulation NMS Adopting Release 34-51808 (opens in a new tab) Checked .
- U.S. Securities and Exchange Commission. Staff Report on Algorithmic Trading in U.S. Capital Markets (2020) (opens in a new tab) Checked .
- ESMA. Questions and Answers on MiFID II and MiFIR investor protection topics (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.