Sept 16 (Reuters) - Investment management firm Invesco Ltd is in talks to merge with State Street Corp"s asset-management business, the Wall Street Journal reported here on Thursday, citing people familiar with the matter. State Street’s asset-management unit manages nearly $4 trillion in assets, as of June 30. Invesco declined to comment, while State Street did not immediately respond to a Reuters request for comment. (Reporting by Sanjana Shivdas in Bengaluru; Editing by Anil D’Silva)