I have no doubt that the gold price is slapped around by large traders from time to time. Some of those traders are definitely American, so it is not surprising when it happen in their time zone.
For the most part, it is opportunistic trading. If the bid is thin, a large trader can slap the price down to panic and shack out the weak long positions so they can buy it back lower for a quick day trade.
I don't think that you should read too much into this of thing. It is just the “noise” of the market. If it didn’t happen, day traders would have nothing to do!
