Buoyed by steadying remarks from the Fed chairwoman, decent earnings reports, and passage of a bill to raise the nation’s debt limit, stocks rallied last week. The S&P 500 has wiped out almost all of its loss for the year from a trying January. Stocks had slumped because of concerns about the outlook for growth in China and other emerging markets and worries about the US economy. Stocks got a lift Tuesday when Janet Yellen, the new head of the Federal Reserve, said she would continue low-interest rate policies and as Congress moved toward raising the borrowing limit minus last year’s drama. US markets will be closed on Presidents’ Day.