Morgan Stanley announced Friday its long-expected plans to spin off its Discover credit card operations in an initial public offering.

It was not immediately known how much the nation’s second-largest investment house expected to raise from the IPO, which Chairman and Chief Executive Officer John Mack had promised would be undertaken after he took the leadership at Morgan Stanley in June 2005.

Discover, which recently announced a new version of its cards, called Motiva, is the fourth-largest debit and credit card network, after Visa, MasterCard and American Express.