I have tick data for backtesting. Each trade lists the Exchange on which the trade occurred. Here is the list of possible Exchanges: AMEX (NYSE MKT) NASDAQ OMX BX (Boston) National Stock Exchange (Cincinnati) ISE (International Securities Exchange) DirectEdge A DirectEdge X Chicago NYSE ARCA (formerly Pacific) NASDAQ IEX NASDAQ OMX PSX (Philadelphia) BATS Y-Exchange, Inc. BATS NASD ADF (FINRA) Market Independent (SIP - Generated) Consolidated Tape System The last three do not appear to be normal Exchanges. What are they, and in what circumstances would a trade be reported as occurring on them? Thanks.
NASD ADF (FINRA) - https://www.finra.org/filing-reporting/alternative-display-facililty- ADF, on Lightspeed Trader we use ADFN, is for Dark Pools and alternative networks to report trades.