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. A deal is not imminent, and the discussions might not result in an agreement, the WSJ reported. It isn’t clear what the terms of a potential deal would look like, but it would be one of the industry’s biggest in recent memory, given State Street’s asset-management unit manages nearly $4 trillion in assets, according to the report. Invesco declined to comment, while State Street did not immediately respond to a Reuters request for comment. Shares of Invesco, which has $1.5 trillion in assets under management, rose 6.5% in extended trade, while State Street was up 2%.