When a large block of stock needs to be bought/sold on the open market rather than jobbed then it is placed on a dark ecn with parameters on pricing and size and time so as not to affect market prices. Much of the dark pool you will see on level 2 with fractional pennies between spread to other ecns. That's how it used to work may have changed somewhat
What are you talking about? Many dark pool and block trades are reported hours late, some more than 24 hours after the fact, and with false timestamps: https://www.elitetrader.com/et/thre...t-trades-more-than-24-hours-late-aapl.328584/
The exact rules are here: https://www.finra.org/industry/trade-reporting-faq See Q100.9 Trades outside of normal market hours have different reporting rules.
So I suspect that not everyone abides by these rules, possibly having a good reason or possibly not. Possibly I'm missing something as well. I do see plenty of transactions on tapes that don't match any recent stock price (within minutes, sometimes hours), especially from some exchanges that seem notorious for late reporting and especially after hours. I think I've seen some explanation somewhere else and will try to find it again, but we also know there are some notorious "manipulators" who don't mind paying fines: https://www.chicagobusiness.com/finance-banking/citadel-securities-fined-over-trading-data-errors
See https://www.elitetrader.com/et/thre...t-trades-more-than-24-hours-late-aapl.328584/ (someone moved my post from here to that stock forum) And that exact transaction has no flags except being form-T (after hours) but reported more than 24 hours late and with falsified time-stamp showing that it’s not delayed.
The post appears to show a screenshot with no trade flags at all and lots of aggregated trades. You need to see the individual trades and the flags (condition codes) on each one.
@Mnewton. They can be. But all trades need to be reported within the reporting parameters. US$200K+ penalties.