David Cohen is taking over as chief risk officer of Commonwealth Bank, replacing Alden Toevs, who will "retire from the role" in June, after eight years as CRO.Cohen will move from his role as CBA's general counsel and group executive for corporate affairs. He took the job as the bank's chief lawyer in mid 2008, moving from AMP where he was also general counsel. Cohen was a partner with Allens Arthur Robinson for 12 years before moving to AMP.Cohen "has increasingly become involved in key risk decisions and processes at CBA, and so this is a logical next step for him and for the bank," CBA chief executive Ian Narev said in a statement on Friday, which may betray some sensitivity to Cohen's somewhat abstract background for his new job, with no line management experience in any banking discipline.Toevs will remain on the bank payroll. Toevs "will continue to work with the CBA Group for at least two years, focusing particularly on balance sheet management and quantitative analytics. He will also be a director on subsidiary boards," CBA said in the statement.