The Rock Building Society yesterday reported a $2.3 million net profit after tax, up a third on the corresponding period, and says it is on track to meet full year NPAT of $4.2 to $4.5 million.The lending book increased 3.6 per cent in the previous six months to $1.15 billion with arrears falling to 0.94 per cent. Growth in retail deposits was lacklustre at only 2.9 per cent.Managing director Derek Lightfoot said in a company statement that, "The Rock will also continue to access wholesale funds on attractive commercial terms until 2009 through our strategic alliance with St George Bank."Capital adequacy decreased to 11.5 per cent from 13.9 per cent for the corresponding period, with liquidity 14.6 per cent compared to 23.8 per cent, and the cost to income ratio is now 76.5 per cent, down from 80.0 per cent.A ten-cent interim dividend was announced, up one cent on the corresponding period.