An analysis of bank funding costs and pricing practices by the Reserve Bank of Australia confirms that banks have managed profit margins effectively over the course of the credit crunch and subsequent global downturn.The overall conclusion of the RBA is the same as any reader of bank financial statements can confirm: the net interest margin of major banks, at an average of 2.27 per cent at the March 2009 half year, is slightly higher than prevailed before the crisis.Commonwealth Bank's willingness to lift its standard home loan rate by 10 basis points last Friday (reversing a slight pricing advantage it maintained for the first half of the year) kicked off another bout of complaints, by the Australian government among others, over the conduct of banks.The RBA analysis, published in the monthly bulletin yesterday, sums up the data on margins and reviews spreads between deposit and lending products.On the net interest margin the RBA reminds readers that the financial statements of major banks show that net interest margins for their Australian operations increased nine basis points in the March 2009 half year and follows a rise of five basis points in the NIM in the September 2008 half year. Since the switch to a looser monetary policy in September 2008, and on the onset of the global financial crisis, the RBA estimated that the interest rate on the aggregate of major banks'  liabilities  declined by an average of about 330 basis points. The RBA said this was about 95 basis points less than the fall in the cash rate over the same period. The RBA estimated  the major banks  reduced their variable housing lending rate (for new home loans) by an average of 385 basis points since September 2008. This is less than the reduction in the cash rate of 425 basis points, but more than the reduction in their average funding costs of 330 basis points.The weighted-average interest rate on the major banks' stock housing loans fell by around 290 basis points, less than the reduction in the variable housing rate, reflecting the fact that over 20 per cent of housing loans are at fixed rates, the RBA said. Interest rates on personal loans to households fell by 170 basis points.Sketching out the level of rate cuts to small business borrowers is harder. Using fixed-rate loans to small business as a proxy the RBA noted that the weighted average cost of small business loans fell by 230 basis points since September 2008.For larger businesses, which often have variable rate loans tied to benchmarks such as the bank bill swap rate, the RBA estimated that two-thirds of borrowers in fact realised a cut of 350 basis points on their loans, in line with money market rates.Banks are seeking to increase margins on business loans, though, with banks having repriced about one-third of their outstanding large business loans the RBA said.