After eight straight days in the black, stock markets are tipping into the red, with the Dow Jones Industrial Average (DJINDICES:^DJI) down just two points and the S&P 500 (SNPINDEX:^GSPC) down 0.12% as of 3:20 p.m. EST. Economic news was mixed, and earnings failed to lift the rest of the market.

The Department of Commerce said durable-goods orders rose 4.6% in December, handily beating expectations. Orders for big-ticket aircraft boosted the numbers, and if we exclude those, orders still rose 1.3% -- not terrible, but not exactly bullish. Pending home sales fell 4.3% last month, according to the National Association of Realtors -- another mixed signal from housing. The housing market has been in a strong recovery for more than a year, but recent data suggests a slowdown may be taking hold.

Caterpillar (NYSE:CAT) is leading the Dow today, climbing 1.8% after reporting earnings. The earnings report showed a 7% drop in machinery and engine sales -- the company's biggest market -- and a 55% drop in profit following a large writedown. But the market was expecting even worse results, and it shrugged off weak guidance and focused on an earnings beat, driving the stock higher.

Alcoa (NYSE:AA) is an other big mover on the Dow today, dropping 1.6%. The company signed a deal to supply fasteners to a Chinese aircraft-maker, but this isn't a huge driver of earnings for the company. Alcoa has made some big moves recently, and Caterpillar's tepid comments are likely what investors are worried about today.

Boeing (NYSE:BA) has fallen 1.2% today after U.S. and Japanese regulators concluded an investigation into the 787 Dreamliner's batteries with no significant findings. The investigation will continue, with control circuits being the next area of focus. This has to be a little unnerving for investors, because there aren't any clues regarding the many issues with Boeing's new flagship aircraft.

Fool contributor Travis Hoium has no position in any stocks mentioned. You can follow Travis on Twitter at @FlushDrawFool, check out his personal stock holdings or follow his CAPS picks at TMFFlushDraw

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