Wall St. declines as oil prices drop; Fed in focus

With the earnings season coming to an end, investor focus will shift to Yellen's speech on Friday at the annual central bankers' meeting in Jackson Hole, Wyoming to see whether the Fed is keen on raising interest rates in the coming months. The case for an imminent rate hike was strengthened by Fed Vice Chairman Stanley Fischer's comments that the U.S. economy was close to hitting job and inflation targets. Oil prices fell more than 2 percent, retreating from last week's two-month highs, on worr