Investment management firm Invesco Ltd. (NYSE:IVZ) is in talks to merge with State Street Corporation (NYSE:STT)s asset-management business, a source familiar with the matter told Reuters. The discussions between both the companies are at an early stage, the source added. 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 that State Street's asset-management unit manages nearly $4 trillion in assets, according to the Wall Street Journal that first reported the development. Invesco declined to comment, while State Street did not immediately respond to a Reuters request for comment. The news follows State Streets deal announcement last week to buy investment bank Brown Brothers Harriman & Cos (BBH) investor services business for $3.5 billion. Shares of Invesco, which has $1.5 trillion in assets under management, rose 6.5% in extended trade, while State Street was up 2%.