Over the last 30 years, Melbourne Cup day has been the equal most likely day of the year for the Reserve Bank to move interest rates, and there are few signs the bank is about to change that.

On Tuesday, the RBA is expected to cut the official interest rate to 0.10 per cent from 0.25 per cent, but this time, attached to the rate cut, there is likely to be the biggest monetary policy decision in decades, with a bond-buying program of about $143 billion expected to be announced.