By Hugo Dixon
The author is a Reuters Breakingviews columnist. The opinions expressed are his own.
The desire for the weekend would normally be among the motivating factors for hoping for a quiet day on Friday, particularly after the week the markets have endured - China continuing to melt down, Greece getting ready to go down the rabbit hole, the NYSE experiencing a three-hour halt as a result of a software update - if only the weekend didn't pose its own special danger. And before that, Janet Yellen stands in the way too, so the relief won't come for investors until that's done.