Commonwealth Bank has lost the head of one its largest divisions, with the announcement yesterday that Ian Saines, group executive for institutional banking and markets, will leave the bank at the end of the year.No news of where Saines might be headed emerged in the media coverage yesterday.Saines has been with CBA since 2004 and was appointed to his current role in March 2009.Institutional banking and markets contributes between 15 and 20 per cent of the bank's profits each year, and is CBA's third largest division, after retail banking, and business and private banking.CBA's chief executive, Ian Narev, will be looking for a new divisional head who will be more aggressive in pursuing growth in the institutional business arena. At the presentation of the bank's 2011/12 results last year, Narev said the bank was underweight in the institutional market, a situation which, he said, did not make sense.