Wall Street edges up; Yellen's testimony awaited

U.S. stocks edged up at the open on Thursday after Federal Reserve Chair Janet Yellen said the central bank could raise interest rates "relatively soon". Yellen is scheduled to testify on the economic outlook before the congressional Joint Economic Committee at 10 a.m. ET (1500 GMT). Investors, however, will be more interested in her view on the economic impact of President-elect Donald Trump's proposed fiscal policies.