This should help you sleep at night
http://skoptionstrading.squarespace.com/storage/short%20intraday%20long%20overnight%20vs%20gold.jpg?__SQUARESPACE_CACHEVERSION=1326600787282
"Back in August 2010, we presented an idea proposed by our friends at SK Options trading for a very simple trading strategy: being long gold in the overnight session, and shorting it during the day. At the time of writing, such a strategy would have returned $2.16 billion from a $100 million initial investment in 10 years, a 37.46% annualized return. Today, we provide a much needed follow up to this quite stunning divergence. As SK notes: "we have revisited the article and written an update. Not only does the discrepancy still exist but it has been actually increasing. That fund would now be worth $5.26B, way up from $2.16B when we last wrote about it - in other words an increase of 143% in just over a year. When we wrote about this in August 2010, the annualized return of the Long Overnight/Short Intraday gold index was 37.46% since the start of 2001. However if we measure from now the annualized return since 2001 is 43.24%, with the annualized return of the Long Overnight/Short Intraday gold index standing at roughly 64.4% since 2009." So for those who wish to layer on an additional alpha buffer on top of what is already the best performing asset of the past decade, the SK Options way just may be the strategy. As for the reasons for this gross arbitrage - who cares. Is it manipulation? is it the early Asian buying offset by London pool selling? It is largely irrelvant - the point is that this is "the divergence that keeps on giving" - kinda like a Stolper trade, or an inverse Tilson ETF, and until it doesn't, or until something dramatically changes in the precious metal market, it is likely that this trading pattern will continue for a long time."