Does anyone understand how penny trades are executed? For example, I sometimes will place an order for 50K+ shares two cents or so above the ask and nothing will happen. My order will sit there for seconds (maybe 20-30 seconds) before only a few fill... maybe 5K or so. Why does this trade sit there for so long? Why isn't part of it executed sooner? Is there a share number cut off where they don't have to show your order or something? If so, what is the limit? I would really like to understand the fundamentals behind how penny stock trades are executed. I've tried to research this online but can't find any information about this technical nature of trade execution for penny stocks.