By TheStreet Staff The Arena Group adds 25 million new users across key verticals; Sports Illustrated Media Group moves up to No. 4 among all U.S. sports properties. The Arena Group (AREN) – Get Arena Group Holdings, Inc. Report, publisher of Sports Illustrated Media Group and parent of technology-powered media properties including TheStreet, reports it posted the largest overall audience in its history in January, based on Comscore data. The Arena Group properties saw more than 112 million unique visitors for the month, moving the company up to No. 34 in the U.S. rankings, nearly 60 places hi…