Stocks roared higher at the open Thursday one day after a set of blowout tech earnings and a pledge from the Federal Reserve to leave monetary policy easy for some time. The Dow Jones Industrial Average gained 172 points or 0.5% to open near 33,992, while the S&P 500 added 0.8%, roughly 33 points, to start trading near 4.216. The Nasdaq Composite index jumped 153 points or 1.1%, trading near 14.204. Apple Inc. shares gained after the bell after the company beat expectations and upped its share buyback program, scoring it a round of price-target increases from Wall Street analysts. Jobless claims also continued to trend downward, falling to 553,000 in the most recent week.