A hot real estate market in Watertown saw the top 10 agents sell more than $5 million in properties, and the top one nearly reached $20 million. According to the real estate sales in Watertown from the multiple listing service (MLS), the top agent for 2016 was Ari Koufos of Realty Executives, who sold 29 properties for $19.49 million. The data comes from MLS, and includes both home sales and rentals. Koufos said he has been the top selling agent in Watertown for more than 10 years. He entered the real estate business in 1997, and is broker and owner of the Realty Executive office in Watertown.