The conference had teased its attendees about a mystery guest who would appear on stage with Icahn. The identity was a secret until Ackman came on stage following remarks by Icahn. Facilitating the meeting Wednesday was CNBC's Scott Wapner, who conducted the vitriolic phone interview between the two men last year.
Wapner on Wednesday presented both men with special T-shirts. They said "Bill and Carl reunited" on the front "It feels so good" on the back.
Ackman and Icahn agreed on the importance of activism in improving companies.
"We want the businesses we own to thrive after we exit," Ackman said. "We can speak the truth without fear of losing a 401(k) account."
Icahn briefly weighed in on Herbalife, the stock the two have battled over (Icahn is long and Ackman is short).
"I'm proud of it...we haven't sold one share," Icahn said of his investment. He declined to comment further.
"It's not about winning," Ackman said on Herbalife. "I would love to find a way to get Carl out of this stock."
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The two men were not always so nice to each other.
"I've really sort of had it with this Ackman guy," Icahn said at one point during their CNBC fight last year.
"Carl, you think I want to invest with you?" Ackman charged later.
"I wouldn't invest with you if you were the last man on Earth!" Icahn bellowed in an exchange typical of the exchange's tenor.
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