Ackman proposed a takeover of real estate developer Howard Hughes for $85 a share and said he is displeased with its recent stock performance.

Billionaire hedge fund manager Bill Ackman announced plans to build a modern-day Berkshire Hathaway ( BRK.A 1.68%) ( BRK.B 1.79%). Although Ackman and his investors would own most of it, it would be available to invest in as a publicly traded company.

Ackman has unveiled his vision to form a new business out of Howard Hughes Holdings “that would acquire controlling interests in operating companies.”