Exotic metals such as cobalt, vanadium and molybdenum may be the next targets for investors in the world's overcrowded commodity markets according to a .

More hedge funds are knocking on the door of trading firms to try to find a way to take a position in cobalt. Unlike copper and nickel, though, cobalt is not traded on an exchange. so the market can be opaque and accurate pricing data hard to find.

An alternative to buying the metal itself is to buy stock in a company that produces cobalt, said Marcus Edwards-Jones, managing director of brokerage Lloyd Edwards-Jones. "If you want to trade cobalt, the best thing is to buy a big chunk of Camec (CFM.L:)" he said, referring to a London-listed company that, among other projects, mines cobalt in the Democratic Republic of Congo.

The advantage of buying shares in a company that produces more than one metal is that should prices fall in one market, the negative impact on share price could be offset by a price rise for another commodity it produces, he said.