What is an intermarket options sweep?

An intermarket options sweep (ISO, or sweep-to-fill) occurs when a broker splits an order into many parts in order to get the best possible pricings currently offered on the market.

An intermarket options sweep (ISO, or sweep-to-fill) occurs when a broker splits an order into many parts in order to get the best possible pricings currently offered on the market.

These orders can often be filled across multiple exchanges and the broker will continue to fill the order lot by lot, always for the best possible price, until the order is completely filled.

A sweep might stand out because they imply some entity (or entities) wanted to enter specific options contracts regardless of their price, as they were focused only on having their entire bulk order filled as quickly as possible.

All 'Sweeps' can be identified by the label in the Flag column

The term 'sweep' is commonly misused. Any trade labeled as a 'Sweep' has been given this label by the exchange that executed the trade.

However, this term is commonly used to reference repeat options activity (that is not expressly labeled a 'Sweep').