Recent Market Anomalies is pointing to some intervention by the G7:

I have reviewed statements of finance ministers from the G7 nations in which they admitted they were undertaking secret actions out of the public eye for fear that public knowledge of their actions would destroy the very effectiveness of their actions. To me, this sounds like an incredible admission of propping up action.

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Furthermore, within the past several months, enormous drops in U.S. stock markets that have been triggered by overwhelmingly negative earning news and macroeconomic statistics at market opening have inexplicably experienced miraculous mid-day turnarounds time after time after time despite the absence of any positive news. What possibly can cause investor sentiment to turn on a dime and spur indexes that have plunged by 250 or 300 points at the opening of markets to perform inexplicable rallies in intra-day trading to recover all losses by market close?

I've been wondering why on bad news the market goes up and this article might give some insight.