What is the IBKR ATS?

IBKR clients can add liquidity and interact with our retail order flow by direct-routing their US equity and index options orders to the IBUSOPT destination. Orders routed to IBUSOPT will be held at this liquidity-providing destination, and will be eligible to participate in an exchange auction to potentially fill against other SMART-routed marketable orders from IBKR clients…

Currently, the IBKR ATS only supports US Stock orders for stocks trading over USD 1.00. 

Find out more in the IBKR ATS order page. …

Interactive Brokers uses its SmartRouting system to determine the best execution venue(s) for each order. For some products, IBKR customers may directly route their orders to a particular market of their choice. IBKR also operates an Alternative Trading System (ATS) in accordance with SEC Regulation ATS, on which it executes IBKR customer trades against each other or against one or more professional liquidity providers who send orders into the IBKR ATS. Order executions on IBKR’s ATS eliminate exchange fees and may offer price improvement compared to the NBBO. …

IBKR Lite clients will not be able to select SMART routing for orders in US stocks outside of the Overnight; such orders will be routed through Lite where possible.

For all other orders entered by an IBKR Lite client SMART will need to be selected when available since direct routing of an order is not supported…