Midday Report: Fed's Yellen Warns of 'Brexit' Consequences

U.S.stocks were in flux as Federal Reserve Chair Yellen warned of an uncertain economic outlook. The Fed will continue with a 'cautious approach' to interest rates, particularly with a potential 'Brexit' muddying its outlook, Yellen said in testimony to the Senate. CVS Health (CVS) - Get Report announced plans to expand its healthier foods initiative to more than 2,900 stores. The drugstore chain distinguished itself as the healthier alternative after banning tobacco sales in 2014. Carmax (KMX) - Get Report fell after missing quarterly estimates on its top- and bottom-line. The auto parts retailer suffered from a rise in expenses that ate into its profit margins. Planet Fitness (PLNT) - Get Report was lower after announcing a secondary offering of up to 10 million shares of Class A common stock.