I was watching jupm this morning at the open. As the price went down, the bid exceeded the ask and stayed that way for maybe 5 minutes intermittently. But the stock was still trading down continuously. I've been paper trading for about a year now since I lost my edge, so naturally I'm confused. Have the rules changed or is there some kind of manipulation going on. How can I trade when the bid and ask are crossed. An explanation would be very much appreciated.