My small sell order for a small Chinese delisted stock with extremely low volume, got executed at IB with a small price improvement on OTCLNKECN on a day when the stock price doubled (my limit price was about at the bid/ask midpoint before it doubled, about half the quoted price after it doubled). My order was not reflected in the bid/ask quotes. I'm unclear what the small price improvement was based on - if a market maker could have picked up my order at my limit price. I entered a larger sell order for the same stock at Fidelity, which got routed to GTS SECURITIES, and is reflected in the real time bid/ask quotes at Schwab. I'm unclear what exchange the bid/ask quotes are based on, and what exchange (if any) GTS SECURITIES forwarded my order to, or how the quotes make if from the market maker to the quotation system (if the market maker doesn't forward my orders to a specific exchange). Would be glad if someone has more insight.