The New Zealand dollar gained half a US cent overnight, but then resumed its downward slide.
ASB Bank head of external foreign exchange sales Tim Kelleher said the rally did not last after traders examined the details of the global dairy trade auction.
"We saw that the volumes sold were 11 percent lower than last auction. Given that the prices were flat, it's probably not as good as it appears on the surface."
A short time ago, the New Zealand dollar was trading at 81.83 US cents, 90.17 Australian cents, 50.24 British pence, 0.6317 euro, 87.74 yen and 5.03 renminbi.
New Zealand shares were mostly weaker today with the benchmark Top 50 Index falling 47 points to 5142.
Murray & Co director of wealth management Johnny Cochrane said the market was quiet as investors awaited the outcome of Saturday's general election.
"Some bargain hunting today from Xero and Xero up slightly, and some relatively good second quarter sales results from Restaurant Brands."
Xero's price rose $1.67 to $21.35.
Restaurant Brands rose seven cents to $3.42.
Infratil was down three cents at $2.65.
Heartland fell four cents to 98 cents.
Sky City fell 12 cents to $3.61.
And Spark fell 10.5 cents to $2.945 cents.