The Cardinals acquired Ferguson from the Reds on Monday in exchange for $250,000 in international bonus pool money, Jeff Passan of ESPN.com reports.
Ferguson will help the bullpen from the left side after the Cardinals traded JoJo Romero (abdomen) earlier Monday. The 30-year-old Ferguson has collected a 4.01 ERA and 22:11 K:B over 24.2 frames for the Reds this season and is an impending free agent.