A survey of leading fund managers has highlighted doubts about the returns from commodities over the next five years, with those bullish about commodities prices halving since last year.

According to the Towers Watson Global Survey which covers 141 investment managers with an average of $109.8bn under management, the number of fund managers saying they were bullish about commodities over the next five years fell from 71% in 2010 to 35% this year.