Yellen will quit when Powell is sworn in

Yellen announces she will leave the Fed board when her successor is sworn in.

She had the option to continue as a Fed governor until 2024. In her announcement, she said she is 'gratified' by the economy's progress since she was sworn in and promised a smooth transition to Powell.

Powell's confirmation hearing is next week.

On policy, Yellen said the economy is close to achieving its dual objectives.