That was the tale of the tape this week, when bulls on everything from Treasuries to equities and credit took lumps in one of the year's fiercer bouts of concerted selling. Even with Friday's bounce in bonds, an exchange-traded fund tracking equities, fixed income and commodities still managed to cough up its second-worst week of the year.

Behind the deluge was a steady ramping in speculative positioning that had left traders exposed to the least dose of bad news, which came in the form of a Fitch Ratings' downgrade of the US sovereign credit rating that followed hawkish central bank posturing in Japan.