Major US stock markets opened Friday's trading session slightly higher, following the revised up Q1 GDP. However, the main focus of attention in markets today is likely to be a speech later from Janet Yellen. At the session start, the Standard & Poor's 500 Index and the Dow Jones Industrial Average jumped 0.11%, opening at 2,092.30 and 17,847.20 points respectively, whereas the Nasdaq Composite Index grew 0.07% to 4,905.40 points.