Banks may need to curtail their rate of return to help restore the social contract that binds financial institutions to their customers, Guy Debelle, assistant governor of the Reserve Bank of Australia, said last night.Debelle framed a lecture at Deakin University around the turmoil caused by the global financial stresses of the last five years and some of the remedies needed to restore trust in financial institutions.He adopted a bleak tone in the opening of his talk, noting, at least in the context of European banks' straitened circumstances, that "diminished trust in political and economic institutions is a particularly worrying development [and] I fear that the path back will be a long one."Debelle called for a series of changes on the part of banks. These included:-- Greater transparency of banks' balance sheets, though "the transparency and the disclosures clearly need to be credible to reduce the information asymmetries." -- More comprehensive regulation and more intensive supervision and scrutiny by prudential supervisors (which is already occurring). -- "A change in management practice at financial institutions [that] must start at the top… The practices that became pervasive throughout the first part of this century that contributed to the excesses need to change."More controversially, Debelle also said that "the rate of profitability in the financial sector is also a debate society needs to be having.""If financial institutions are perceived to be earning too high a rate of profitability, particularly if the institution is enjoying a degree of support from the public sector, that too will impede the restoration of trust."