The market was below trendline after Thursday, heading lower when they just pumped the euro overnight, triggering stock futures buying. All the technical weakness was erased. This is not fantasy, but empirically provable. But of course, Dunrunnin will say, "the Fed doesn't buy stock futures", yet clearly no natural price discovery was going on yesterday. They jammed it from the open, forcing stock covering. Breadth went from under 50% positive to more than 90% positive in seconds. And that's how the technicals remained all session.
Unless you enjoy losing money, you should never hold any short positions overnight in this market. Too much positive momentum behind it, and the Fed can jack it up any time it wants by trashing the dollar.