After marching along the comeback trail Wednesday afternoon, stock proxies once again found themselves far below break-even midday Thursday. There were some fundamental reasons for the decline, but traders also were overlooking some positive developments, which is a marked change from recent trends. As of 1:39 p.m EST, the Dow Jones Industrial Average was down 1.1% to 8639.81, the S&P 500 was lower by 1% to 908.74, while the Nasdaq Composite was off 0.9% to 1418.01. Issues weighing on shares included lackluster November retail sales, cautious comments from Gateway ( GTW), and heightened prospects for a bankruptcy filing by UAL ( UAL) after the Air Transportation Stabilization Board rejected its application for a $1.8 billion federal loan guarantee. Gateway was lately down 15.8% and UAL was off 69.6% before being halted. Additionally, there are worries about Intel's ( INTC) midquarter update after the close, Friday's employment report, as well as the approaching deadline for Iraqi compliance. However, the declines also came amid some positive news developments, including a larger-than-expected, 50-basis-point rate cut from the European Central Bank, another drop in weekly jobless claims, and some upbeat comments from Advanced Micro Devices ( AMD). A few weeks ago, such a combination of news would have sent shares skyward, particularly those of the chip and related groups. AMD lately was up 4.7%, but the Philadelphia Stock Exchange Semiconductor Index was down 0.4%, further evidence that the worm -- and the mood -- on Wall Street have turned to the negative, at least for the time being. Heading toward the close, it will be critical to see whether the S&P can recover above support at around 910, as was the case Wednesday , or whether selling will accelerate and take the index to a test of even more critical support at 900. Thus far, the index has traded as low as 905.90.