Fresh concerns over the dollar and the ability of the US to finance its current account deficit arose on Wednesday after foreign portfolio inflows for the first time in a year fell below the liabilities implied by the trade deficit.

Data from the Treasury show net inflows to the US totalled $48.1bn in October, down from $67.4bn in September and less than the record $55.46bn trade deficit for the month revealed on Tuesday. The US relies on foreign purchases of US portfolio assets to finance its current account deficit by covering the outflows in trade. It was the first time in a year that portfolio investment had fallen below the level necessary to cover that gap.