The billionaire investor has filed to take his hedge-fund firm public in tandem with a new investment fund.

The planned listing would give public investors a stake in Ackman's investment platform, which oversees a concentrated portfolio of large-cap companies

Billionaire investor Bill Ackman is taking his firm, Pershing Square Capital Management, public on the stock market while launching a new investment fund that aims to raise billions from everyday investors and major financial institutions.

In a combined offering, investors who buy shares in Pershing Square USA ( PSUS) will also get shares in PS. For every 100 PSUS shares purchased, the buyer will get 20 shares of PS at no extra cost. The offering doesn't allow direct purchases of PS shares.