Yes, investors are flocking to gold exchange traded funds (ETFs) as the dollar weakens.

Case in point is streetTRACKS Gold Shares (GLD): after gold surged to a record $992 an ounce earlier this week, the fund traded nearly 11.5 million shares, reports Joanne Von Alroth for Investor’s Business Daily. No one is particularly surprised, though.

What is surprising is the performance of white metals.

Platinum, in particular, has continually hit record highs. On Tuesday, it rose to $2,275 an ounce, and is up 50% year over year. The supply has also taken a hit from the continuing power supply problems in South Africa, which are interrupting mining activity. In addition to that, there has been a platinum deficit since 1999. Mining gets about 7 million ounces of platinum a year.

Why, with all of this shortage and growing investor demand, is there no platinum ETF available in the United States? We’ve been getting a lot of questions from our readers, so we put the question to Kevin Rich, CEO of DB Commodity Services.

"[Platinum] is not liquid enough to support an ETF," is the simple answer. "There are not enough players transacting it."

The last thing anyone would want, Rich says, is for a fund to take money in but find that it couldn’t buy the underlying asset. Platinum is scarce enough that it’s possible for an investment product to take away the supply. "When you bring in an ETF, you make sure the supply and demand of the commodity are still driving the market," Rich says.