Taffee - I don't suppose you were watching level 2 for WH Smith (SMWH) this morning, were you? I get a condensed version from CMC.
I've noticed this now and again on other stocks. What happened this morning was the stock opened and dropped to where it had been a few days ago after a bit of a run up. All of a sudden the offer price jumped from 408p to 423p. Lower offers quickly came in to fill up the book, but loads of trades started going off at between 412 and 415 or so and the bid became the offer several times (flip-flopping of the spread I guess you could call it). Then the price settled down and trade dried up. Price drifted back down but eventually came back up to about yesterday's close.
There was no news or RNS. Nothing. The only thing I did notice was that the early morning drop had taken it below a rising trend line which now looks a bit more intact.
Is this possibly just tree-shaking to trigger short stops before a further fall, do you think?