The Corner | May 11, 2015 | Yellen’s words about stocks being overvalued and bond yields too low was a signal that investors should not expect to enjoy the Fed’s cheap money forever. ECB’s policymakers have also warned about risks in the financial system that can arise in a situation of protracted low interest rates and abundant liquidity. “It is positive that central banks may be working together to avoid potential bubbles, yet the problem isn’t stocks but bonds,” Bankinter analysts pointed out.