Augie, I believe that the difference between the XAU and the HUI is that the XAU has a mix of precious metal producers (both gold and silver) while the HUI is made up of miners who are primarily gold miners. There seems to be a lot of overlap, but HUI seems to corrolate to POG a little better.
augieboo: HUI is dominated by miners who have not hegded their positions, and XAU is overweight in the ones who have, i.e. NEM.That's why HUI moves better with GOLD