BETHESDA, Md.--(BUSINESS WIRE)--Walker & Dunlop, Inc. announced today that Mark Washington has joined the firm as managing director of Capital Markets, Multifamily Investment Sales, based in Seattle. Washington will lead multifamily investment sales across the Pacific Northwest, marking Walker & Dunlop's sales entry into one of the most actively traded multifamily markets in the country. Seattle was among the most active institutional multifamily markets in the U.S. last year, ranking N. ...