THE Dow Jones industrial average has nose-dived more than 500 points, or over 3 percent, since the Federal Reserve chairman Ben S. Bernanke’s somewhat upbeat, if ambiguous, statement on the economy on Wednesday. Hurrah!

Many interpreted his remarks — which followed a two-day meeting of the Fed’s policy-making committee and which noted, among other things, that the Fed expected the unemployment rate to decline to around 7 percent next summer, from its current perch of 7.6 percent — as signaling the beginning of the end for the controversial program known as quantitative easing, or Q.E., now in its third round. That program, in which the Fed has purchased tens of billions of dollars of Treasury and mortgage-backed securities a month, has kept interest rates at rock bottom since 2008, and helped propel stock and bond prices to their recent heights.

But since Mr. Bernanke’s remarks, the dominant market sentiment hasn’t been euphoria, but fear.

What happened to change the mood so dramatically, so quickly? Is the panic selling justified — or is it just the first glimmer of hope that the Fed will finally take the metaphorical morphine drip out of the arm of the capital markets and allow the forces of supply and demand to set long-term interest rates?

Before answering those questions, it might be useful to review what exactly Mr. Bernanke said. First, he said that there should be no immediate change to the stimulus program. He said the economy looked as if it was slowly improving, that Fed officials saw signs that employment was picking up and that the inflation rate was hovering below the Fed’s target of 2 percent.