Has Janet Yellen Jumped the Shark Already?

Has Janet Yellen jumped the shark already?

That appears to be the case after Ms. Yellen, the Federal Reserve chairwoman, testified before Congress last week that in the face of insatiable demand from investors for higher yields — because of the Fed’s continuing zero interest-rate policies — the Fed would use nothing more than its supervisory authority over the big Wall Street banks to try to rein in excessive risk-taking.

What Ms. Yellen should be using to stop the mispricing of risk in the market for financial assets is her unique ability to raise interest rates. But she seems determined not to do that.