That means that their policies often have a more significant impact (and certainly a more immediate and measurable one) on the price of, say, junk bonds than they do on job creation and wages.

That is always true, but it has never been more true than lately, with the Fed deeply engaged in unconventional steps to try to increase economic growth, leading to nearly $4.5 trillion in assets ending up on the central bank’s balance sheet.

Image Alan Greenspan, former Federal Reserve chairman. Credit... Alex Wong/Getty Images

To some degree, the whole point of that exercise was to drive up the prices of stocks and other assets to encourage economic growth. But a major risk all along has been that the efforts would raise asset values to bubble territory without accompanying economic growth.

If you believe that is happening, there are two options. One, embodied in a speech at the University of Southern California on Wednesday by the president of the Dallas Fed, Richard W. Fisher, is to pull back on money printing. But if you believe that the Fed needs to keep doing everything it possibly can to get stronger growth, then you are left with a few other options. One, which Ms. Yellen has repeatedly emphasized, is regulating banks and other financial institutions well to ensure that even if a bubble does emerge, and pop, the rest of the economy does not go down with it. There is no reason that somebody paying too much for junk bonds or social media stocks now needs to cause a recession in 2016, in other words.

Another option is to use “open mouth policy” (as opposed to the usual “open market policy”), jawboning markets to try to rein in excesses that might create risks. It is not an outlandish idea. The economist Dean Baker has argued that if Mr. Greenspan had made full-throated, public arguments that there was a housing bubble in 2004 and 2005, it might have led to fewer people stretching to buy homes and less damage when the bubble eventually popped.

But it does amount to a government official substituting her own judgment for that of the marketplace, the prices arrived at by thousands of buyers and sellers for an app maker or a leveraged loan.