Scepticism over the level and sustainability ANZ's returns from its operations is a long-running theme of this newsletter's coverage of the bank, and a view beginning to find an airing among influential sell-side analysts.Accordingly, ANZ's management took an assertive stance yesterday in explaining the sources of its profit and the merit of the bank's "super regional" strategy.One theme was the deepening of relationships with institutional banking customers, with volume growth and cross-sell exceeding growth in customer numbers, which were up 11 per cent."In international and institutional banking, a third of our institutional clients are now using ANZ in more than one country," the bank's chief executive, Mike Smith, said."For large clients… almost 90 per cent of our top 100 customers use ANZ in more than five countries."Smith said that "together this has seen Asian income [from institutional banking] grow from 24 per cent to 34 per cent" over the past three years.He also said that cross-border income was growing three times faster than local income.Shayne Elliot, ANZ's chief financial officer, told the investor briefing the bank could earn a return on equity of "up to 25 per cent" from business and corporate customers by managing their trade flows in Asia, with the bank often providing loans, foreign exchange, operating accounts and deposits, all of which, in combination, earned much higher ROEs than the lowly ROEs of six per cent common on trade finance. ANZ said its cash profit from Asia (a geography it rolls up with Europe and North America) was A$989 million or 15 per cent of the total. Operating income from Asia was 17 per cent of the group's total.These proportions are still less than the targets of 20 per cent and even 30 per cent mooted in the past by Smith.