Mysterious Fill
I had an oddly sized GTC order that had been around for quite awhile that has just filled completely at the pretty attractive price that it had been set at. Since it was an odd size order the full size of it was not shown on the quote feed. Yet it filled completely with neither a shortage nor an excess executing. I am trying to understand how an order like it would fill the way it did since anyone initiating the trade would seemingly not know the odd lot portion of the order that was hidden. Its possible I suppose for someone to initiate a market order for the exact quantity but it does seem passing strange. The trade executed on EDGX whatever that may mean. As a shot in the dark I might speculate that it could be my brokerage firm did the match as they would know the size of the order while no one else would. In any case it was a good fill at the time but of course who knows what the future holds. Since I use Fidelity for most of my trading I'll let the cat out of the bag to reveal that detail. What I have heard is that Fidelity is a bit more customer friendly on trading than other brokers & this fill could be an example because of its favorable nature.