When the market’s in a correction, it’s typical to see a strong open morph into a weak close. That’s exactly what happened Thursday as stocks erased early gains. The market got off to a decent start, cheered by an unexpected drop in weekly jobless claims. But that data point was offset by news that the U.S. was considering air strikes in Iraq. The Nasdaq rose 0.6% early but got turned away at its 50-day moving average.