I've been using CashApp to direct deposit and auto-convert my paycheck each week into Bitcoin. I've heard through talking to some Coinbase folk that they are the orderbook under a lot of services like CashApp. I imagine that it would be trivial for them to look at their configured customer inflows and predict demand. They know that every week on the same day of the week, around the same time of day, my direct deposit goes through and is configured to convert a certain amount of dollars to Bitcoin. Combining that will all of the customer settings would provide a weekly/bi-weekly/monthly spike trend for demand, which they could use (or sell the knowledge of) to acquire more bitcoin from other exchanges just before the demand spikes. They might even be acquiring all the time, and pausing just before the spike to avoid acquiring at a higher rate. Does this sound too conspiratorial? It would require that they play on their own order books to take real and I'm not sure that Coinbase does that...