> I am curious: based on your experience, do you think that, in principle, an omniscient observer of all transactions on stock exchanges and who made them could

> I am curious: based on your experience, do you think that, in principle, an omniscient observer of all transactions on stock exchanges and who made them could answer questions like this in many cases? If so, what concrete things would they hypothetically want to look at to figure it out? Not necessarily, because the order flow they see goes through brokers, is anonymized, and order execution is optimized algorithmically as to not reveal any patterns. You can't easily tell what is retail flow and what isn't, however you want to define that. What you would need is not just to exchange data, but also the internal user data from companies like robinhood, and an understanding of how exactly algorithms from hedge funds and HFT firms behave. In theory this would be possible if you had complete access to and a full understanding of all of this. In practice it's impossible.