Rajat GuptaBy Julie DiMauro and Stuart Gittleman

NEW YORK, June 18 (Thomson Reuters Accelus) - The insider-trading conviction of Rajat Gupta, a former McKinsey group chairman and a-list board member, had federal prosecutors and securities regulators glowing. But companies face stiff challenges protecting their boards from breaches confidentiality by directors and the reputational and other damages that ensue, consultants and lawyers said.