Quote from Sam Mcgee:
I noticed one trend with gold. If you compare the daytime trading price with the nighttime price, you'll see over the last few years, it will go up slightly on average during the day and on average it will go down during the night. (eastern standard time)
I'm guessing that what's happening is that the United States is slowly selling off it's gold and it is being bought by Aisia. The Americans are doing most of their selling during their daytime hours and the Asians are buying during their daytime.
I can't remember the exact numbers but I think the average increase each night was around 0.2% and the decrease each day was around the same. I would expect this trend would continue for years as the US has a lot of gold that it can sell to Asia. If the average gain is more than your trading cost, you could go long every night and sell every morning. Perhaps there are other daily trends that you could combine the strategy with.