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 markets just can't make up their minds on how to handle the government shutdown, as the Dow Jones Industrial Average (^DJI -0.11%) has fluctuated all over the map today. After falling to kick off the morning session, the Dow has bounced back with moderate gains in the afternoon. As of 2:15 p.m. EDT, the blue-chip index has gained more than 40 points.

You can't control how an unpredictable market will affect your portfolio based on what Washington does, but you can keep an eye out for your stocks. Let's catch up on all the market action you need to know about.

AT&T thinks big
AT&T's (T 1.88%) making the most of today's gains: The telecom stock has picked up 2.4% to lead the Dow. The stock has actually been one of the worst performers on the Dow year to date as the telecom giants have fallen off the pace recently. However, today investors are cheering news that AT&T is reportedly closing in on selling off its wireless towers to Crown Castle International (CCI -0.03%). It would be the second major recent pickup for Crown Castle, which late last year purchased 7,200 of T-Mobile's wireless towers for more than $2 billion.

For AT&T, the move would bring in considerable cash as the company heightens its ambitions to keep up with highflying rival Verizon. Some analysts believe the deal with Crown Castle could fetch up to $5 billion -- a sum that would help offset AT&T's pricey $14 billion network upgrade. In addition, AT&T is sniffing around Europe for expansion: The company's CEO said this week that the region could be a giant opportunity in the mobile broadband market with the right regulatory reforms.

Time will tell whether AT&T pulls the trigger on a major acquisition or expansion like Verizon did with its purchase of Verizon Wireless, but AT&T shareholders can be confident for now, with the firm due to repurchase $11 billion in shares at an opportune time for this slumping stock.

Nike's (NKE 0.66%) flying high as well today on the heels of its earlier stellar earnings report, but company CEO Mike Parker refueled the stock's momentum by announcing at the firm's analyst meeting today that Nike could hit $36 billion in annual sales by 2017. That's a jump of more than 42% over the company's fiscal year 2013 performance, when it grew sales to $25.3 billion for the year.

Can Nike do it? The company certainly impressed with its most recent quarter, and if it can keep European and North American sales momentum strong, it'll have a chance. But Nike will need to turn around an important Chinese market that has slumped recently, and the firm will have to fend off hard-charging competitors such as Under Armour.

Still, that ambitious target is a good sign for investors, who have been rewarded with two consecutive fiscal years of EPS growth. If Nike can reinvigorate growth in China and its footwear segment, its largest business by sales that has seen growth slow to single digits last year, it'll be on pace to impress investors for years to come.