Rare earth metals like lithium and cobalt have been among the hottest commodities in recent years, but there are no actively traded contracts to help negotiate efficient pricing, adding to volatility in related lithium ETFs that track companies dealing with these metals.

For instance, the Global X Lithium & Battery Tech ETF (NYSEArca: LIT), which tracks the full lithium cycle from mining and refining through battery production, has declined 13.7% year-to-date.

Market weakness has also negatively affected the recently launched Amplify Advanced Battery Metals and Materials ETF (NYSEArca: BATT), which includes companies involved in the production of advanced battery technologies, such as lithium and cobalt. Over the past week, BATT declined 5.0% while LIT fell 2.7%.

Unlike most other commodities, lithium and cobalt don’t have actively-traded futures contracts tied to the metals, so investors are forced to rely on costly services that provide price estimates, which may differ from privately negotiated chemicals prices used by large miners and Chinese battery manufacturers, the Wall Street Journal reports. The uncertainty in pricing could further add to rapid price swings in the markets.

“The market is quite opaque,” Nick Page, a portfolio adviser for Fiera’s European division, told the WSJ. “It’s difficult to take any comfort from all of the different forecasts, which makes it more risky.”

Rare Earth Metals Supply & Demand

Meanwhile, supply and demand for the rare earth metals can move dramatically since they are tied to how quickly consumers adopt new technologies like electric cars, a trend that is still in the nascent stages.

The market for lithium and cobalt has surged to as much as $10 billion from about $4 billion two years ago. Analysts project the figure could double again by 2025.

Some analysts argue that the unreliable pricing could benefit the biggest players in commodities, such as Swiss trading giant Glencore; the world’s largest cobalt supplier, and global chemical heavyweights Chilean Sociedad Quimica y Minera de Chile S.A.; and U.S.-based FMC Corp. The firms have existing relationships with refiners and battery makers concentrated in China, the industry’s dominant player. Gaining exposure to producers is currently the easiest way for smaller investors to play battery metals.

For instance, LIT includes FMC 18.2%, Albermarle Corp 15.3%, Quimica Y Minera Chile 7.2% and Tesla 5.6% among its top holdings. BATT’s top holdings include Albemarle Corp 3.5%, Sociedad Quimica Minera Chile 3.4% and Glencore 3.1%.

For more information on the materials space, visit our basic materials category.