June 16 (Reuters) - U.S. based private equity firm Advent International is nearing a deal to acquire a minority stake in money-management firm Fisher Investments, the Wall street journal reported on Sunday.

The deal could be unveiled by Monday, valuing Fisher at nearly $13 billion, the report said citing people familiar with the matter.

(Reporting by Devika Nair in Bengaluru Editing by Chris Reese)