Bill Ackman is moving forward with plans to build a modern-day Berkshire Hathaway just as Warren Buffett prepares to step down from the company he took over and built into a $1.16 trillion investment holding company more than 60 years ago. Ackman's Pershing Square Holdings (LSE
SH) will invest $900 million in Howard Hughes Holdings, boosting its stake in the real estate firm from 37.6% to 46.9%, the companies said on Monday.
