Although we don't believe in timing the market or panicking over daily movements, we do like to keep an eye on market changes -- just in case they're material to our investing thesis.

The Dow Jones Industrial Average (DJINDICES:^DJI) posted a second straight day of triple-digit losses Thursday, as a combination of weak earnings, rising interest rates, and chaos in Egypt sent stocks spiraling downward. While that trifecta may sound like a sure-fire reason for a sell-off, all is not lost: A seemingly major sell-off like today's still leaves the Dow up more than 17% year to date, and jobless claims last week fell to the lowest number since 2007. The Dow tumbled 225 points, or 1.5%, to end at 15,112 Thursday. 

Caterpillar (NYSE:CAT) was the only stock in the index ending in the green, ticking up 0.1%. With the recent results from rival Deere being applauded by the markets today, Caterpillar benefited from its presence in the same industry. With Deere's farm machinery sales jumping 60% between 2009 and 2012, Wall Street figured now might be the time to invest in machinery makers. 

Wal-Mart (NYSE:WMT), however, lost 2.6% as the retailer's second-quarter results underwhelmed. Not only did sales disappoint, but the company also lowered its expectations for this fiscal year, as several other major retailers missed investor's expectations. Wal-Mart, of course, faces increasing price competition from online retailers, as well, threatening its future margins. 

Hewlett-Packard (NYSE:HPQ) dropped 4.5% Thursday, as tech stocks were the worst performers of the day, falling more than 1.8% as a group. Some of the worst news for HP investors today didn't even come from the company itself: Dell's profits dropped 70% last quarter, an ominous sign for fellow PC makers. 

Cisco Systems (NASDAQ:CSCO), incidentally, didn't help the tech sector, either, plummeting 7.2% after a discouraging earnings call in which the communications giant announced it would be trimming 5% of its workforce. Despite the slowly recovering economy, CEO John Chambers called the environment more "mixed and inconsistent" than any prior recovery he's ever seen. While the cautious tone dismayed some investors, it's important to remember that Cisco's earnings are still growing nearly 20% a year -- for the time being.