Here are two gold ETFs: SPDR Gold Shares ( GLD) and iShares COMEX Gold ( IAU).

There is no difference between the funds except that GLD has 30 times the assets and volume of IAU. While GLD is larger, both funds have high liquidity. Investors can buy and sell shares of both GLD and IAU near their underlying values.

Silver

Here are two silver ETFs: Silver Trust ( SIVR) and iShares Silver Trust ETF ( SLV).

SLV is a well-established physical silver ETF, with more than 8.5 million shares changing hands on an average trading day. SIVR was just launched this summer and will take time to garner investor interest that is comparable to SLV. While SIVR is gaining speed quickly, investors should stick to SLV until the new fund is more established.

Futures ETFs

These funds, which hold gold futures contracts and are organized as partnerships, belong to a group of exchange-traded products that have come under intense scrutiny in recent weeks. The CFTC is currently considering limitations on the number of futures contracts that certain funds can own, limiting the size of some exchange-traded products.

None of the three products listed below is conspicuously large. The two ProShares gold funds, however, could face double regulations in the future. Since they are futures-based, they could suffer from a CFTC crackdown, while their leverage could draw the ire of FINRA.

They are taxed as futures, with 60% at the long-term capital gains rate and 40% at the short-term capital gains rate. Investors will be responsible for taxes on these funds each year and will receive a Schedule K-1 form.

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