Sometimes I have seen on these markets (where approx £100K or so has been matched) large unmatched trades (back or lay) of £1K, 2K etc sitting a few ticks away from the current price either on the lay or back side of the ladder. The other unmatched trades either side of these walls of cash are generally around £80-£150ish.
My question is this:
1 Is this a cumulation of numerous closing back/lay trades from various traders who all (by happenstance) think that the price will move there?, or
2 Is it a trader who has matched a large sum elsewhere chancing his arm and closing it off with one large sum (unlikely as I assume such traders would drip feed)?, or
3 Is it someone trying to stop the market price moving beyond that particular level (be it back or lay)?
If 3 what is the trader hoping to achieve here?
Your comments and thought are very welcome

Thanks