Depends on your broker, my friend. I'm talking about those that invest with an actual broker, not Schwab (no offense, I don't use an actual broker either). I'm assuming someone saw the 4,999 bid, not what broker placed that bid. Some private brokers go from per trade commission to per share commission on 5,000+ share blocks. I don't personally know anyone who has a broker with the 5,000 block scenario, but I do know people who have brokers that alter commish based on share volume or price per share. I wouldn't read too much into the 4,999. It can be related to frequency trading, but there can be tons more at play here.