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.

As we move into the sixth day of the Dow Jones Industrial Average's (^DJI -0.98%) winning streak, many are wondering how much higher the index can go and if the Santa Clause rally is for real. The Dow is up another 92 points, or 0.57%, as of 1 p.m. EST, while the S&P 500 is higher by 0.38% and the Nasdaq has climbed 0.28%. Some individual stocks are struggling while others are outperforming the market. Let's take a look at both.

Shares of Blackberry (BB -3.14%) are having a bad day after what had been a few days of upward momentum following the company's earnings announcement last week. The stock is off by more than 5% today after BlackBerry co-founder and former CEO Michael Lazaridis announced he had sold about 3.5 million shares and now holds less than 5% of the struggling smartphone-maker. Additionally, Lazaridis said he has officially ended his bid to buy the company. Most analysts who have commented on this move call it a smart one, as they don't believe the stock has much hope of heading higher and shares are fairly liquid at this time. This move should tell other investors that they -- much like the founder, who surely knows what's happening at the company -- should consider cutting back on their positions or getting out completely. 

MasterCard (MA -0.08%) reported this morning that it was a good holiday season for retailers. The credit card company's data indicated that holiday sales between from Nov. 1 to Dec. 24 were up 2.3% from the previous year, compared to an increase of only 0.7% last year during that time frame. This announcement means that the fourth quarter may be much better for retailers than many investors and analysts were predicting at the start of the season. Shares of MasterCard are higher by 0.9% this afternoon.  

All that shopping ended up creating too much shipping for FedEx (FDX -0.21%) and UPS (UPS 0.53%), which weren't able to live up to the guaranteed shipping they had promised so many customers around the country. Thousands of Americans didn't receive last-minute gifts as the carriers were overwhelmed by packages the days leading up to Dec. 25. Many disappointed customers voiced their frustration on social-media platforms. But UPS and FedEx didn't buckle and force their employees to work on Dec. 25, which most customers, even those missing packages, applauded. Shares of the carriers aren't being punished, as FedEx is higher by 0.73% and UPS is down only 0.08% today.  

Editor's note: A previous version of this article incorrectly stated that Blackberry co-founder Michael Lazaridis had sold a majority of his shares. The author and The Motley Fool regret the error.