Weeden & Co. is exploring the sale of all or part of its business, including its prime-brokerage division.Sources said the Greenwich, Conn., broker-dealer is in talks with investment bank Piper Jaffray. The initiative follows months of negotiations last year over the possible sale of Weeden’s prime-brokerage operation to a blockchain-technology company. That deal never closed.“Nothing is carved in stone,” one source said of the...