A former London banker, his wife and a friend have been sentenced in a $NZ4.5m insider trading scheme uncovered by the UK's Financial Services Authority.

Housing lending fell in December, month-on-month, for the first since Reserve Bank records began.

The RWC will add about $700m to the NZ economy over its six weeks and if NZ wins it could boost general confidence, Alan Bollard says.

The NZ dollar rose as Reserve Bank Governor Allan Bollard held the official cash rate at 3 per cent as expected amid signs the economy is in need of support.