With Greece imploding, the last thing we need is for the US market to do what it did when Dubai faced a near-death experience in November. Whether or not that is the reason, we don't know, but someone just purchased a massive order of ES futures contracts in the open market, causing a dramatic spike in the market.
Even absent this spike, the volume in ES has been quite healthy, regardless of the drop in global markets overnight.
Here is a longer-term comparison of what happens when Liberty 33's gloves come off.
Regardless of the cause, the goal has been accomplished: the upward intraday trend in the dollar has been definitively broken.