RE: Late buy4 Dec 2018 17:08
Seer, that £1,1 m was the uncrossed trade ( UT)...just ignore it in terms of buy / sells. After 4:30pm, traders with Direct Market Access ( paid for facility) have 5 extra mins to make offers to buy/ sell (rules apply to stop silly offers)
At 4:30 there are buy/ sell orders on both sides of the book. The computers try to complete as many orders , starting with the biggest values. Once this period of time has passed, the computers derive a closing price for pre opening trading approx 5 mins before 8:00 when we start trading.