Summary List Placement Bill Ackman discussed his loss-making investment in Warren Buffett's Berkshire Hathaway during a virtual speech at the Sohn Hearts & Minds conference this week, according to the Australian Financial Review. "We have probably lost more money in Berkshire than anyone in the world," the billionaire investor and Pershing Square chief said. Pershing Square invested in Buffett's company in the second quarter of 2019, held a $1 billion stake at the end of March, and sold the entire position by May.