Grant Spencer will serve a six month term as acting governor of the Reserve Bank of New Zealand from late this year. Graeme Wheeler, the current governor, has now made it clear that he will step down at the end of his five year term. Spencer will also then step down.Given the general election slated for September 2017, the government and RBNZ board concurred on deferring selection of a new governor.Spencer has always been "perhaps the most over-qualified deputy governor in any major central bank in the world," commentator Sean Keane of TTT Consulting wrote yesterday.He has run the financial markets division of both the RBNZ and ANZ New Zealand, Keane said, and is also "the RBNZ's expert on macro-prudential policy and housing market matters."