After some confusing trading on Wednesday, the markets sent a crystal-clear signal on Thursday that the word of the year is "down," as in fall down, take down or (if this keeps up) maybe even meltdown. Reversing the prior day's closing-hour gains, the markets dropped sharply in the final hour. General Motors ( GM) issued disappointing 2005 earnings guidance, and news hit that the Treasury Department was limiting the use of money brought back into the country under the corporate tax cut law approved in October. The Dow Jones Industrial Average lost almost 112 points, or 1.1%, to 10,505.83. The S&P 500 fell 0.9% to 1177.45, and the Nasdaq Composite dropped 1.1% to 2070.56. Oil prices rose almost 4% on Thursday to $48.04, the highest since the end of November. Knocking on $50 a barrel again helped energy stocks. Coal and oil topped the charts on the back of oil's strong advance while homebuilders benefited from lower interest rates and a positive outlook from MDC Holdings ( MDC) issued after Wednesday's close. Airlines, technology and pharmaceuticals were weaker. Apple ( AAPL) rose 7% after its earnings blowout, but this did nothing for the rest of the sector. Higher oil prices obviously hit the airlines, and a Food and Drug Administration letter warning Pfizer ( PFE) on its TV ads had drugs in a funk. Pfizer dropped 3%. Drug companies also were expected to be big repatriators of foreign earnings, along with technology companies. The Treasury Department ruled that companies bringing cash back to the U.S. from abroad wouldn't qualify for the huge tax break if the money were used for dividends or stock buybacks. There was some evidence that the ruling hurt certain stocks: Hewlett-Packard ( HPQ), one of the biggest proponents of the tax cut and a company with almost $15 billion that could be brought home, fell about 2% in the late afternoon.