what is the exchange FINRA?

some orders were filled at ISLAND, ARCA, NYSE, but some orders filled at FINRA, what is it? in IB, when submitting an order, i can select exchange to send the order, but there is no FINRA option.

 

FINRA is not an exchange, it is the Financial Industry Regulatory Authority.

 

Some older info here: https://www.elitetrader.com/et/threads/finra-trades-and-interactive-brokers.290001/

 

FINRA is a self-regulatory organization (SRO) that regulates brokers and broker-dealers. They also have many other responsibilities such as running the Trade Reporting Facility (TRF).

There are light markets (NSDQ, BATS, NYSE, EDGX, ARCA, ect) and dark markets (dark pools). Remember, all transactions need to be reported. When you are looking at the T&S and you see a FINRA print, you are looking trades executed in a dark pool. I'm oversimplifying, but you get the point.