Cushman & Wakefield, one of the world's largest privately held commercial real estate services firms, has promoted David Leviton to the position of executive director, Transaction Services. Leviton, who joined Cushman & Wakefield in 1991, was previously a senior director. He is based in the firm's Long Island office located in Melville, N.Y. Throughout his career, Leviton has negotiated complex office leasing transactions on behalf of tenants and landlords and facilitated office building sales in the Long Island region. Tenants he has represented include the State of New York, Equitable Life, Citicorp, Winthrop University Hospital, South Nassau Hospital, Fidelity Investments, Level 3 and Sprint. On behalf of landlords, Leviton has completed the successful leasing and marketing of properties totaling more than four million s/f. Most notably, in 2005, he completed one of the largest transactions in Long Island history with the 454,000 s/f lease for North Shore Long Island Jewish Hospital at i.park in Lake Success, N.Y.