What Is FIX?
FIX stands for Financial Information eXchange. It is the standard language that financial institutions use to send messages to each other: orders, trade confirmations, market data, cancellations, and more.
Think of it like email, but specifically designed for trading. Just as email has rules about what a valid message looks like (a subject line, a sender, a recipient), FIX has rules about what a valid order or confirmation looks like. Every major bank, broker, and trading venue speaks FIX.
Why does it exist?
Before FIX, every firm had its own way of sending and receiving trade messages. Two firms that wanted to connect had to write custom code just to understand each other. As trading became faster and more global, this was unsustainable.
FIX was created in the early 1990s as a common standard. Today it's used by thousands of institutions worldwide. When your firm wants to connect to a new trading venue, the venue almost certainly expects FIX.
Two sides of every FIX connection
Every FIX connection has two sides:
| Role | Who they are | What they do |
|---|---|---|
| Initiator | The side that reaches out | Your system connects to the venue's server |
| Acceptor | The side that listens | The venue's server waits for incoming connections |
Most of the time, your firm is the Initiator, connecting out to a venue. Sometimes, when a counterparty connects to you, your firm is the Acceptor, running the server while they connect in.
Conncentric handles both roles.
What is a FIX session?
A FIX session is a live, persistent connection between two parties. Once established, it stays open and messages flow back and forth continuously. If it drops, both sides have logic to reconnect and reconcile any messages that may have been missed.
Each session is identified by three things the venue gives you:
- SenderCompID: your firm's identifier on this connection
- TargetCompID: the venue's identifier
- FIX Version: which version of the protocol to use (e.g., FIX 4.4)
You get these values from the venue's connectivity team when you sign up.
What does Conncentric do with FIX?
Conncentric manages the FIX connection on your behalf. You give it the connection details, and it:
- Establishes and maintains the session
- Handles reconnects automatically if the connection drops
- Keeps heartbeats running so the venue knows you're still there
- Receives inbound messages and delivers them where you need them
- Takes messages from your systems and sends them to the venue
You configure this once in the Portal. After that, it runs on its own.
Do I need to know FIX to use Conncentric?
For most setups, no. You need the connection details from your venue (host, port, SenderCompID, TargetCompID, FIX version), and Conncentric handles the rest.
If you need to filter or transform specific FIX message types or fields, the Pipeline Designer uses plain field names and values, so you don't need to memorize tag numbers.
For more complex custom logic, the Plugin SDK is available for developers.