Commonwealth Bank has made a significant strategic hire with the appointment of high-profile tech sector executive Andrew Lark as chief marketing officer.Lark, a New Zealander with a global career footprint, joins the bank from Dell, where he was vice president responsible for leading the global marketing of its Public and Large Enterprise Group.  CBA's decision to hire Lark stems in part from his experience in social media strategy garnered from an earlier role at Dell, where he led the communications and online operations at the world's largest e-commerce site, Dell.com.   His appointment suggests that CBA, which has languished behind competitors on the social media front, may be about to shake things up. Lark posted on his blog that "helping lead one of the most important brands Down Under is both exciting and a privilege. Commonwealth is one of the largest and most profitable banks in the world, the largest Down Under and like us (Dell) is growing nicely. They have more satisfied customers than their three largest competitors combined. Their marketing team is strong having launched a terrific brand campaign. And, best of all, they are a Dell customer."Lark first worked with Dell 19 years when he was a senior VP consultant at PR firm Fleishman-Hillard. Prior to Dell, he was at tech start-up LogLogic. He has also held global marketing roles with Sun Microsystems and Nortel.Lark serves on the board of New Zealand's largest and most successful venture capital firm, No 8 Ventures.He joins the CBA on July 1 and will report to the group executive for retail banking services, Ross McEwan. Lark replaces former CMO Mark Buckman, who left the bank last month to join Telstra as CMO.