The Chicago Board of Trade on Thursday moved a step closer to becoming a public company when 99 per cent of its 3,600 members approved a plan to make the 157-year-old futures exchange a for-profit entity.

Yesterday's vote clears the way for the second-largest futures exchange in the US to vote as early as next month on going public. The move would come almost three years after its crosstown rival, the Chicago Mercantile Exchange, did the same - subsequently seeing its shares more than quadruple. At current seat prices, the CBOT would be valued at about $2bn.