It's not so much what the companies like G and Barrick produce. It's tied to the price of Gold on the market on any given day. People are selling into golds strength and buying back in on the drops.

Not too many stocks or funds are doing this in the current market so if you have lots of money to put into gold you can make a decent buck every few days, week, bi-weekly etc.. If you think of gold as a stock it's the only thing moving in value right now. If you noticed in the last few months on any particular day you see a large sell-off on gold followed by drops, but the nice thing is that it currently always pops upwards again. It's a great tool for making money if you can afford to buy a large enough quantity of gold. JMO