Without intending to — and perhaps without even realizing it — the normally cautious Fed head Ben Bernanke may have launched a major tightening policy during his news conference on Wednesday. The de facto policy shift immediately sparked a rout on Wall Street, with stock, bond, and gold prices all plunging. And it’s going to shake up confidence even more, perhaps even slowing the already anemic recovery.

Mr. Bernanke has stumbled into a major policy mistake.

Read my full column here.