WASHINGTON (AP) — Federal Reserve officials are seeking to calm investors by assuring them the Fed won't start trimming its bond purchases until the economy has strengthened. They say any pullback in the Fed's stimulus will hinge on the economy's performance, not a calendar date.

William Dudley, president of the Federal Reserve Bank of New York, says that if the economy proves weaker than the Fed forecasts, he expects the bond purchases to continue.

Chairman Ben Bernanke jolted investors last week when he said the Fed will likely slow its bond-buying this year if the economy continues to improve. The bond purchases have helped keep interest rates low.

Jerome Powell of the Fed's board in Washington says separately that investors appear to have incorrectly concluded that the Fed will taper its purchases soon.