The tight price action after lunch is because the specialist has accepted the order from a major client to either buy or sell a large block today and committed to an average PPS to get the commission and future business. Some days it will carry over to the next day which may be today's case since it went into the close.. It's called throttling but the big question is whether it was a buyer or seller? Typically if it is at the low end of the range that day its a sell order but by the volume count maybe only 500,00 shares. If it is continued the specialist will gap it up in the morning and then sell against it to complete the order and price point.