JACK BRENNAN is Chairman Emeritus and Senior Advisor of Vanguard, one of the world's largest investment companies. He served as Chief Executive Officer from 1996 to 2008 and Chairman of the Board from 1998 to 2009. He is a sought-after speaker on investing and finance and received his education at Dartmouth College and Harvard Business School. JOHN WOERTH is a Senior Communications Advisor to Vanguard. He spent more than three decades in corporate communications at the company and served as its chief spokesperson for 15 years. He holds degrees in journalism from Temple University.