Morgan Stanley Group will offer 19% of its stock.

The firm said the first public offering of stock in the 51-year history of the investment company will consist of 4.5 million of its common shares. In a preliminary prospectus, the holding company of Morgan Stanley & Co., the investment banking firm, said it expected the offering to be priced at between $42 and $46 a share, which would raise $189 million to $207 million.