Gold prices quickly reversed after the US stock market open.

A large volume of gold trading is via ETFs now and the timing of the fall suggests that was the culprit.

gold intraday

gold intraday

There hasn’t been much fundamental news. Yesterday, gold producers in South Africa reached a tentative deal with workers but that had little immediate impact.

The moves are more likely related to positioning ahead of Yellen on fear about a possible hawkish headline. Broad US dollar strength is also weighing.