The Reserve Bank's influence over long-term interest rates is limited by global investor activity, and it may need to call on further macro-prudential tools to assist with policy, according to governor Graeme Wheeler.
New Zealand's central bank hiked the official cash rate 100 basis points to 3.5 percent earlier this year, and is currently assessing the impact of those hikes, but that has had little impact on longer-term mortgage rates, which have followed long-term rates in major economies lower, Wheeler said in a speech in Wellington today.
While the yield on New Zealand's 90-day bank bill rate has climbed to 3.7 percent from 2.91 percent at the start of the year, the yield on the 10-year bond has dropped to 3.93 percent from 4.76 percent over the same period.
Wheeler said "long-term interest rates are highly correlated across countries" making it difficult for central banks operating with floating exchange rates to run independent monetary policies.
"They can influence short-term rates, but cannot set their own long-term rates," he said. "The Reserve Bank raised short-term rates during the period March to July 2014, but longer-term mortgage rates have fallen as a result of the decline in long rates in the major economies."