"Our intervention was necessary to mitigate systemic risks and protect the broader US banking system," US Treasury Secretary Janet Yellen says during remarks at the annual NABE conference in Washington. Follow Bloomberg for business news & analysis, up-to-the-minute market data, features, profiles and more: http://www.bloomberg.com Connect with us on... Twitter: / business Facebook: / bloombergbusiness Instagram: https://www.instagram.com/quicktake/?...