[kenned3]

This is what CAT was built to address https://www.catnmsplan.com/

you send your order to your broker/dealer, they send it to their OMS, which sends it to Citadel, who sends it to their internalisation engine..

All of these messages, including order Identifiers to create the linkages are sent to FINRA.

So your broker sends order "123ABC" to Citadel, FINRA gets this and can trace your order back up and down the "stack" however they want.

[willdearden]

Ah cool, are the internalized orders reported publicly anywhere or are they just sent to the SEC/FINRA?