Damn the CSPA

After a reasonably promising day of positive trading the closing share price auction invariably knocks the sp down a pip or two back to where the price was at the beginning of the day, or sometimes below it. This is particularly galling especially when the CSPA trades are only worth a few thousand dollars at best. Bots at work maybe or manipulators trying to catch a few stop losses? - either way it is bloody annoying.