Cobley defects from CBA to join Westpac 27 May 2015 3:50PM John Kavanagh Commonwealth Bank's executive general manager, retail products and third party banking, Lyn Cobley, is jumping ship to join Westpac, where she will replace Rob Whitfield as group executive, Westpac Institutional Bank.Cobley served as CBA's group treasurer from 2007 to 2013, before moving into her current role.She has worked at Barclays Capital, where she was head of financial institutions, and Citigroup, where she was head of securitisation.She was the chief executive of Tradingroom, a short-lived joint venture between publisher Fairfax and Macquarie Bank.Cobley will start at Westpac in September.