The proportion of investors who believe the dollar will weaken has almost tripled in the past month as markets brace for a Federal Reserve rate cut, according to a Bank of America survey. Some 23 per cent of respondents to the bank's monthly sentiment survey said their most confident trade was to short the dollar, the highest level this year and up from 8 per cent in July. The dollar has outperformed most G10 currencies this year but its rally has fizzled over the past month as data showed the US economy was losing steam, prompting traders to bet on a sharp cut in US interest rates.