Also you gotta think, these hedgefunds have billions plus high tech. They have ai that models trends, human behavior, game theory, different correlations, etc. They are buying the data from whereever you are trading from. They know how much cash you hold, how much you make, how much your wife makes, how much debt you have, how many shares you can afford to buy and at what frequency, they know your trading behaviour, they know if you have free cash if you are more likely to buy AMC or another stock depending on the day of the week and time, etc...