Federal Reserve Chairwoman Janet Yellen suggested that the central bank might buy more kinds of assets in a future crisis during a speech Friday on the tools available to the Fed to manage the money supply.

In an address prepared for an appearance at an annual conference in Jackson Hole, Wyo., Yellen said that the Fed "may wish to explore the possibility of purchasing a broader range of assets" than it currently does. Although she didn't specifically say so, such assets could include stocks rather than the government bonds the Fed currently is limited to.

Yellen reassured other Fed members and investors that the toolkit the Fed used during the financial crisis — a combination of promising low rates for longer and large-scale bond purchases or "quantitative easing" — would likely be sufficient if the Fed again had to respond to a crisis that persisted even after it lowered its interest target all the way to zero.

But she also allowed that "future policymakers might choose to consider" additional tools, such as the ability to buy stocks.

For the Fed to buy private stocks, Congress would have to pass legislation allowing it to do so. The Fed's purchases are restricted by law. Its large-scale purchases of the past year were made up of Treasury debt and mortgage-backed securities guaranteed by the federal government. Other central banks, however, such as the Bank of Japan, are allowed to buy stocks.

Although buying stocks directly would give the Fed greater ability to boost the money supply, it is also viewed warily because it would risk putting the Fed off picking winners and losers among companies or distorting specific markets.

Yellen also suggested that the Fed might consider raising its inflation target from 2 percent to 4 percent in the future. Some economists, such as Federal Reserve Bank of San Francisco President John Williams, have discussed that possibility recently with the thought that higher nominal interest rates would give the Fed more room to cut interest rates without running into the zero lower limit.

Yellen also referred to the possibility that the Fed might target a price level, rather than an inflation rate, or simply aim to stabilize total nominal gross domestic product. Those aggressive measures have been recommended by economists who have argued that the Fed has accidentally kept money too tight throughout the recession and recovery by not responding to surging demand for dollars.

Any such shift in the Fed's management of money is a ways off, however. Although those are ideas for the Fed to consider, Yellen explained, it "is not actively considering these additional tools and policy frameworks."