Companies have already started signing contracts in other currencies, said Thomas J. Sargent, a Nobel economic prize winner, in response to a question whether it was a risk for the world to have the US dollar as the only reserve currency

He said the selection of trade currencies is subject to the influence of many competitive forces, including technological evolvement, and the outcome will affect global reserve currencies.

"It is important what the US is doing, but it is more important what other economies have done”, Sargent said.

The key is how companies sign their contracts, and gradually more companies have started to sign contracts in other currencies than the US dollar, he said.