As I sit in the Istanbul Airport watching the snow fall outside, I'm reminded of the song by the great Willie Nelson. Some of the best memories of my childhood include singing that song with my father, as we traveled on holiday from campsite to campsite. Today, those words have a much different meaning.

I just drained the last few electrons of my BlackBerry's battery, as I told my family the bad news. My flight has been canceled, and it will be another day before I get home, and another weekend lost in the air.

Analyst upgrades:

• FBR Capital upgraded AutoZone (NYSE: AZO) to Market Perform from Underperform on valuation following the company's Q4 results but lowered its target on shares to $134 from $137.
• Citigroup upgraded Calpine (NYSE: CPN) to Buy from Hold on valuation following Wednesday's sell-off. The firm believes Harbinger's share sale reflects an issue with the shareholders, not with the company, and raised its price target on the stock to $16.50 from $13.
• Credit Suisse upgraded Knight Transportation (NYSE: KNX) to Neutral from Underperform and raised its target to $17 from $16 based on valuation and the improved freight environment.
• Citrix Systems (NASDAQ: CTXS) was upgraded to Conviction Buy from Buy at Goldman.
• Webster Financial (NYSE: WBS) was upgraded to Outperform from Sector Perform at RBC Capital.
• Dr. Reddy's Labs (NYSE: RDY) was upgraded to Overweight from Equal Weight at Morgan Stanley.

MAJOR PAPERS:

• The Wall Street Journal reported that KKR Financial Holdings LLC (NYSE: KFN), a unit of Kohlberg Kravis Roberts, revived concerns of a credit crunch after it asked for a restructuring of billions of dollars in short-term debt.

• According to sources, the Chicago Tribune reported that Deutsche Lufthansa AG (OTC: DLAKY) could look to take an equity stake in a merger between Continental Airlines Inc (NYSE: CAL) and UAL Corporation's (NASDAQ: UAUA) United Airlines.
• The Associated Press reported that the pilots' unions of Delta Air Lines Inc (NYSE: DAL) and Northwest Airlines Corporation (NYSE: NWA) are unable to agree on how seniority for the companies' pilots would work under a combined carrier. The impasse puts the deal in "serious jeopardy," inside sources reported.

• Electronics retailer Sharper Image Corporation (NASDAQ: SHRP) has filed for bankruptcy, citing declining sales and profitability, Bloomberg reported.