Stocks started the day on the wrong foot as more worries from the eurozone surfaced. On Monday the G-20 didn't provide any additional fire power for IMF lending to increase a firewall. Most authorities just said it wasn't a need at this time. But after, Pending Home Sales rose 2% from 95.1 (revised lower) to 97.0. Stocks then rallied reversing the lower gap open. Evidently algos paid no attention to the revision lower of previous data preferring to trade the better headline instead. Since the beginning of 2012, dip buyers have been ubiquitous, as so they were on Monday.
Stocks in the end couldn't salvage a significant gain. The DJIA, just above 13K before the close (and with headline writers furiously writing bullish headlines) "da boyz" stepped-in and pulled away the football. This kind of action is typical HFT nonsense.