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 current state of the labor market isn't anything to brag about, but it seems to be improving steadily. Data today showed monthly jobless claims reached their lowest point since 2007, a stat that gave the S&P 500 Index (^GSPC 0.04%) a reprieve from its five-day losing streak. By day's end, the benchmark index was up 5 points, or 0.4%, to end at 1,698. 

Jabil Circuit (JBL -0.34%) was the S&P's most severe decliner, plunging 9.9%. The components manufacturer is coping with the floundering market share of BlackBerry, which is Jabil's second-largest account. With BlackBerry going private as it struggles to compete with larger competitors, Jabil forecast weak revenue in the upcoming quarter, causing Thursday's sharp sell-off. 

Telecommunications player Windstream (WINMQ) shed 4.3%, though the decline had little to do with fundamental business problems like Jabil's. Windstream's stock went ex-dividend today, meaning that anyone who owned the stock at the market's close yesterday could sell it today and still receive the next quarterly dividend. With Windstream rewarding investors to the tune of $0.25 per share per quarter, about 2.9% of the stock's decline could have been expected..

Lastly, shares of data storage company Western Digital (WDC -0.62%) fell 3.2% a day after news of its CFO's departure broke. Wolfgang Nicki, a man with an exemplary name and a fine track record at the company, has been with Western Digital for nearly 20 years. To add insult to injury, Western Digital shares were taken off Longbow Research's "Best Ideas List," its stock having been vaulted by rival Seagate Technology