SP Manipulation

One thing that we have noticed here in the US is that games are being played on a daily basis with the SP. For example, yesterday in the US the DOW was down about 300 points all day long. Prana held up around 1% all day long - I checked my screen at 4pm and it was up around 1%. A few minutes later, to be exact at 4:09pm a trade went through that pushed the SP down a little over 2% close for the day. A friend of mine that was a trader told me that this is the game they play - all intended to make longs sell - they match the last trades after the close and will sit on the close depending on how many bidders there are. It is happening here too - for PBT and for another stock I follow AHZ. Almost on a daily basis you will see the last trade is a really small share block like 1 share to knock the price down at the end.