CoStar group ended the fourth quarter with earnings of $23 million after a $5 million loss in the third quarter. The company, which provides online marketplaces for commercial real estate, apartment rentals, lands for sale and businesses for sale, spent 2015 “building the premier marketplace for renting an apartment in the United States,” said Andrew C. Florance, Founder and Chief Executive Officer of CoStar Group. Operating expenses including the redesign of apartments.com rose steadily by 60% since the start of the year. According to a company press release, the firm realized $100 million in net new subscriptions in the fourth quarter alone after launching an improved apartments.com website in February and acquiring Apartment Finder in June.