What are the most common ETFs that track the metals and mining sector?

There are two general types of exchange-traded funds (ETFs) that track the metals and mining sector: those that invest in mining companies and those that invest directly in physical metals.

The most common ETFs that track the metals and mining sector include the following:

• Precious metals
• Gold
• Silver
• Platinum
• Palladium 
• Base metals
• Copper
• Nickel
• Steel

A fund that invests in a basket of several precious metals is the ETF Physical PM Basket, which aims to replicate the return of physical gold, silver, platinum and palladium.

The SPDR Gold Trust invests in physical gold and hosts returns that have historically matched the precious metal closely. The VanEck Vectors Gold Miners ETF invests in gold mining companies and uses the NYSE Arca Gold Miners Index as a benchmark. (For related reading, see "Investing in Gold: Mutual Funds Versus ETFs.")

Also available and commonly traded are more exotic ETFs that offer returns leveraged to the price of physical gold or inverse to the price of gold. The ProShares Ultra Gold, which seeks to double the return of bullion and the ProShares UltraShort Gold, which seeks to provide double inverse bullion performance, are examples of types of these sophisticated ETFs.

The largest and most popular silver ETF is the iShares Silver Trust, which holds the objective of matching the return of physical silver. The Global X Silver Miners ETF invests in silver mining companies and seeks to meet or exceed the returns of the Solactive Global Silver Miners Index.

A short silver ETF option exists with the ProShares UltraShort Silver. This ETF seeks to double the inverse performance of the price of physical silver.

An ETF that aims to match returns offered by investing in physical platinum is the ETF Physical Platinum. An ETF that invests in the shares of platinum mining companies is First Trust ISE Global Platinum ETF, which uses the ISE Global Platinum Index as a benchmark. 

A closely related trust, rather than a fund, with returns linked to investing in physical palladium is offered by the Physical Palladium Trust. The trust seeks to match the performance of the price of physical palladium.

A popular base metals ETF with assets of over $220 million is the PowerShares DB Base Metals ETF. The fund tracks the performance of the Deutsche Bank Liquid Commodity Index-Optimum Yield Industrial Metals Excess Return.

Although it is technically a note and not a fund, the iPath DJ-UBS Copper SubTR ETN aims to match the performance of an un-leveraged futures position in copper and is the largest and most actively traded copper ETF.

There are two copper mining ETFs that are popular with investors: the Global X Copper Miners ETF, which seeks to replicate the performance of the Solactive Global Copper Miners Index, and the First Trust ISE Global Copper ETF, which tracks the ISE Global Copper Index.

The most commonly traded pure Nickel ETF is the iPath DJ-UBS Nickel SubTR ETN. Technically, this is a note and not an ETF. It seeks to track the performance of an un-leveraged position in nickel futures.

The Market Vectors Steel ETF (SLX) is a steel industry ETF that seeks to replicate the performance of the NYSE Arca Steel Index.

(For related reading, see "Top 5 Precious Metal ETFs for 2018.")