CNBC | S&P, Nasdaq up 1% on tech rally; Yellen, oil eyed CNBC U.S. stocks traded mostly higher on Wednesday as investors digested remarks from Fed Chair Janet Yellen, as well another choppy trading in oil. "It's a welcomed relief, especially after these past few weeks," said Jon Adams, senior investment ... Yellen: Oil bust aids US economy Oil mixed after OPEC report US stocks end flat after seesaw session amid oil slide |