Sources told Bloomberg the sale remains undecided, but proceeds could be used to meet higher capital requirements in the event of new financial regulations in Europe.
The proceeds may be used to buy a bigger stake in Deutsche Postbank, the sources said.
Deutsche Bank, which currently owns just below 30 percent of Deutsche Postbank, has an option to take a majority stake in the Bonn-based lender by February 2012 via a convertible bond.
Deutsche Postbank Chief Executive Stefan Juette told a banking conference on Thursday he did not know when or whether Deutsche Bank would increase its stake.
A recent report from the Association of German Banks estimated that Germany's 10 largest banks would need to raise about $133.7 billion (€105 billion) if new rules proposed by the Basel Committee on Banking Supervision are enacted as planned.
U.S.-listed shares of Deutsche Bank dropped more than 3 percent in New York trade following Bloomberg's report.