"Ok, then lay out a logical argument for these actions. Why a last-second buy?"

Well I was told by one poster that he/she, when buying more shares, on a day when the sp appears to be getting artificially depressed, will buy a few more on the uptick on the last of the day. So there is one reason....it's about giving a hit for the team in this case. Why in the last second?.....so those with the supercomputers can't zip in for a nanosecond and negate a lift in the sp....except that the fast computer would ordinarily win.