There are a couple of things that cause this type of close. First the month end mark up has a good up bias on the 21st trading day of the month, this is due to what positions funds want to show at months end. You need to have the big gain stocks in your portfolio at months end even if it means you bought them in the last 30 seconds. This is called Window Dressing in the street Jargon.
Second, the PPT is very active at certain times and whenever you see Goldman very active in program trading that is most likely the PPT, they have an account there rumor has it. When you see that skew in their program trading, they are doing the governments manipulation work. They know how bad things are out there, but they need to keep this market up to help sell the story about how much good their actions are doing.
PPT has been around for awhile, and this is how you spot them at work, look for end of the day saves particularly on down days, but this was also the PPT at work. Now that the government has more control over GS it helps them conduct their futures program manipulation at times when they want to do it. GS was also one of the big firms that had the CIT fund accounts that helped manipulate the price of Crude up last year, ducking the CFTC guidelines that would normally apply to Large Speculators by getting commercial status under the CIT label. This allowed them to have unlimited position sizes like commercials have and enabled them to push prices to a ridiculous level.
Commercials are afforded that status due to the hedging nature of their operations, so when the govt mistakenly gave these funds that designation they set the stage for what happened. Of course they then cried foul and blamed the speculators! An acquaintance of mine went before congress to explain all this to them and of course they dismissed him once they realized he was more on top of what had happened than they thought.
