TWO down, two to go. Westpac has joined rival National Australia Bank in hiking mortgage interest rates for investors and owner-occupiers. Interest-only investor loans will be hardest hit, increasing by 28 basis points to 5.96 per cent per annum. Principal and interest investor loans will increase by 23 basis points to 5.79 per cent. The bank will also raise its owner-occupier rate by three basis points to 5.32 per cent, while interest-only owner-occupier loans will increase by eight basis points […]