Just hours before the Reserve Bank's 9am official cash rate review, the currency dropped by US1c to US78.4c, then fell further to US77.7c when the bank released a more "dovish" than expected outlook. At one point the currency was down by 2 per cent from late on Wednesday before recovering a little to US77.9c by 5pm yesterday.
As the bank kept its OCR at 3.5 per cent, Wheeler's repetition of its previous warning about the exchange rate, to the effect that its level remained "unjustified and unsustainable", added to the selling pressure.
"But the lion's share of that [weakness] can be attributed to the US dollar's strength on the back of FOMC's statement," said Bank of New Zealand currency strategist Raiko Shareef.
"The FOMC was more upbeat than anyone had expected and really pushed back against those who expected a softer stance following the global jitters that we had earlier this month," he said.
The bank's comments on rates had "essentially removed a tightening bias".
"The market was already mildly bearish on the NZ dollar and this simply threw fuel on the fire," he said. "It reinforces the message that the NZ dollar does not have too much of a leg to stand on."
BNZ expects the currency to be US78c by the end of this year, falling to US73c by the end of 2015. At yesterday's level, the currency has dropped by US10.4c or 11.8 per cent since hitting US88.36c in July.