I found this short but interesting comment by Tim Iacono on Seeking Alpha about whether changes in GLD's holding have anything to do with the price of gold: http://seekingalpha.com/article/82626-does-gld-inventory-affect-the-price-of-gold
This was a topic I was planning to cover in a future blog because I have seen other commentators analysing GLD creations and redemptions. I feel some caution needs to be exercised with such interpretations. I'll expand upon this in the future, but in the meantime here is my reply to Tim that briefly explains my caution:
I'm a bit wary of reading too much into changes in GLD holdings over the short term because of the inherent lack of transparency in the gold market. As most gold trading is over the counter (OTC) and not all done on a nice visible stock exchange, you can't be sure that positions in GLD are not offset in other markets.
The GLD (or any ETF) redemption/creation process involves costs, so it is more profitable for market makers in GLD to avoid this where possible. For example, where retail investors are selling GLD, the normal (ideal) process is for the market maker to buy GLD from them and sell gold on the OTC spot market. They redeem GLD for physical gold and use this physical to settle their OTC spot sale.
However, if the market maker feels that the sell off in GLD is temporary and that retail investors will come back in the future, then they can make more profit by holding GLD and avoiding redemption/creation cost. They still have to buy GLD and still sell gold OTC so that they do not have a trading position and any exposure to the gold price, but instead of redeeming GLD, they lease gold in the OTC market and use that leased gold to settle their OTC spot sale. Their long GLD position (asset) is offset by a lease (liability). Considering that gold lease rates are 0.2% there isn't much holding cost with this strategy.
The only time a market maker would then redeem GLD for physical gold is if there is sustained selling over a period of time. In this situation the market maker's holding of GLD would continue to grow. They then redeem and use the gold to repay the lease.
As a result, I feel that analysis of GLD's (or any other gold or silver ETF) redemption/creation flows against the gold price is only realiable if done in time period blocks of a month or more.