Commercial real estate broker David Leviton has joined JLL as managing director and market leader of the firm’s Melville office. Leviton had spent the last six years as a senior vice president with CBRE and before that he was with Cushman & Wakefield for 20 years. For his new position at JLL, Leviton will oversee the brokerage firm’s agency leasing and tenant representation business and is tasked with expanding JLL’s market share on Long Island, according to a company statement.