The Journal had said in August that the Financial Industry Regulatory Authority (FINRA) was examining weekly meetings at Goldman Sachs , where research analysts offer tips to traders and then to big clients.
The examination has now been expanded to include ten other firms, the Journal said.
FINRA has sought information of any meetings where unpublished research opinions or trading ideas were disclosed to non-research employees or clients, the paper said.
FINRA does not reveal names of firms that have received sweep letters, the regulator's spokesman Herb Perone said in an emailed response to Reuters.
Citigroup, JPMorgan and Morgan Stanley could not be reached immediately for comment by Reuters.
(Reporting by A.Ananthalakshmi in Bangalore; Editing by Muralikumar Anantharaman)