This may be because Fed policy makers gave no hint of when their rate increases would end.
Fed policy makers meet again on July 1 and 2.
Fed policy makers voted last month to lower short-term interest rates, according to minutes of their meeting.
At last week's meeting, Fed policy makers left interest rates alone.
The challenge of Fed policy makers, she said, "is to make sure that they stay contained."
Fed policy makers are scheduled to meet next at the end of June.
Some Fed policy makers have publicly suggested that it could be 5 percent or higher.
Fed policy makers, as expected, left the central bank's benchmark federal funds rate at 1.25 percent.
Fed policy makers are expected to provide some help by again cutting interest rates when they meet next Tuesday.
Fed policy makers can act, however, at any time between meetings.