Higher interest rate expectations have driven the 2-year swap rate up by 4.5 basis points higher, to 0.77 per cent - its highest level since March last year.
The New Zealand 10-year swap rate was 2bps higher on Friday, to 1.92 per cent.
Smyth noted that the Reserve Bank, in a routine announcement last Friday, planned to buy just $200m in Government bonds this week, down from $1.8 billion a week at the start of the Covid-19 pandemic early last year.
"With nominal government bond issuance stepping up to $500m this week, from 300m previously, this means the market will need to start absorbing more supply," Smyth said.
The market's reaction may provide some clues as to how the market will adjust when the Reserve Bank stops purchases altogether, Smyth said.
"Taking market pricing at face value (a greater than even chance of an OCR hike in November), the implication would be that the Reserve Bank might stop quantitative easing purchases in the coming months, since the RBNZ would want to stop adding to its stock of bond holdings before it starts raising the official cash rate," Smyth said.
The OCR has been sitting at a record low of 0.25 per cent, where it has remained since March last year.
Recent events have encouraged economists to re-assess their interest rate expectations.
First, there was data showing the economy grew by 1.6 per cent in the March quarter -- easily double the most optimistic of expectations.
Then, in mid-June, New Zealand wholesale interest rates bumped up the US Federal Reserve signalled that it expected to start raising interest rates in 2023, driven by faster growth and higher inflation.