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

Expect a solid start to the stock market today, as the Dow Jones Industrial Average (^DJI 0.06%) is set to rise by 42 points at the opening bell. Stocks are continuing to march higher in this shortened trading week, helped along by recent economic data that point to stronger growth for this quarter and into next year. Meanwhile, news is breaking this morning on a few stocks that could see heavy trading in the session, including UPS (UPS 0.34%), Target (TGT 1.28%), and BlackBerry (BB 1.09%).

UPS is in focus after a surge in last-minute online shopping overwhelmed its network in the days leading up to the Christmas holiday. The delivery giant had expected to process a record 63 million packages on Dec. 16 and 17, but saw late-season demand that was "much greater" than forecast, according to The Wall Street Journal. The result is that many customers didn't receive their packages in time for Christmas, leaving UPS and retailers like Amazon.com apologizing to disgruntled shoppers. UPS stock is unchanged in premarket trading.

Target is dealing with its own set of holiday shopping issues. The retailer's hacking attack, which compromised data from more than 40 million credit cards, included the theft of encrypted PIN numbers, according to Reuters. That has the potential to widen the scope of the fraud to include bank account withdrawals, although Target told Reuters "no unencrypted PIN data was accessed" by the hackers. Regardless, the data breach will go down as one of the biggest in U.S. retail history and could pressure the retailer's holiday season results. Target's stock is unchanged in premarket trading.

Finally, BlackBerry stock is under pressure this morning after co-founder Mike Lazaridis officially ended his exploration of a potential takeover bid. According to an SEC filing on Christmas Eve, Lazaridis has terminated his agreement to look into buying the company, and has also reduced his stake in the struggling smartphone maker to less than 5% by selling more than $26 million worth of shares. BlackBerry's stock is down almost 35% so far this year and is lower by 2% in premarket trading.