Quote from ac1987:
There are daily reports that are emailed out to customers, if you have a connection to the dark pool chances are your broker can get you the daily report. They are all sent either an hour or so after the close or next day before the open. They are kind of ambiguous but they will all tell you what the most actively traded stock was in their dark pool on any given day.
I currently get daily emails from Credit Suisse (XFINDER), Knight and UBS but they are probably available from others as well. If you want to see what they emails look like so you can decide if its helpful reach out and ill forward some to you.