There’s a saying in show business: Never follow an animal act. Yet that was the tough task facing Mitchell Caplan, CEO of E*Trade Financial Corp., when he took the floor to deliver a speech at Wharton — with the audience still laughing over the clip from a notorious E*Trade ad that aired during the 2000 Super Bowl. After a chimpanzee in an E*Trade T-shirt danced to “La Cucaracha,” the 2000 ad’s message was “Well, we just wasted $2 million. What are you doing with your money?” The great irony is that in real life, E*Trade’s free-wheeling, free-spending ways at the height of the dot-com bubble nearly ruined the company. “I’m amazed in many respects that E*Trade, or E*Trade Financial, or whatever you want to call it, even exists today,” said Caplan, 49, whose soft, understated delivery was in contrast to the dramatic change in corporate culture that has taken place at E*Trade Financial since he assumed the helm in January 2003. Caplan’s presentation was part of the Wharton Leadership Lecture Series .…