Blackstone Group's $4.75 billion initial public offering is expected to price on Thursday, according to underwriter Morgan Stanley.

The expected pricing date was disclosed by Morgan Stanley on its Web site on a page that lists the investment bank's calendar of pending IPOs.

Blackstone, one of the world's largest private equity investment firms, expects to sell 133.3 million common units at $29 to $31 each for as much as $4.13 billion in proceeds.

Blackstone also will let underwriters, led by Morgan Stanley and Citigroup Inc., to sell an additional 20 million shares to meet any excess demand. That would boost the total offering to as much as $4.75 billion, making it the largest U.S. IPO of the year and the sixth largest ever.

Blackstone intends to list its shares on the New York Stock Exchange under the symbol "BX."