The Dow Jones Industrial Average (DJINDICES:^DJI) had shed more than 68 points as of 11:30 a.m. EST. AT&T (NYSE:T) was one of the worst-performing Dow components, while Plug Power (NASDAQ:PLUG) surged once again, continuing the recent run that has seen shares rally more than 500% just this year. Facebook (NASDAQ:FB) shares also rose to a new all-time high.

Chinese concerns weigh on stocks
The Dow Jones' sell-off appears to be, at least partially, a byproduct of Chinese economic concerns. Chinese stocks dropped sharply overnight as investors weighed a recent string of bad economic data. In particular, Chinese exports in February fell 18% on a year-over-year basis, much worse than economists had anticipated.

Given the size of China's economy, any economic weakness in the Middle Kingdom could hit U.S. companies particularly hard.

AT&T cuts prices
AT&T was dropping alongside its index, down 0.4% in line with the broader market. Over the weekend, the wireless giant cut prices again -- the cost of its 2GB Mobile Share Value plan was reduced to $65, a $15 reduction

A&T's price cuts should help the company add additional subscribers and retain its current subscribers, but could ultimately weigh on the company's profits. 

Facebook gets a new price target
Facebook shares, meanwhile, rallied more than 2.5% early in the session. Fueling Facebook's move was a price target boost at UBS from $72 to $90.

UBS believes Facebook is undermonetized relative to its user base, and that the company should continue to increase its revenue as it becomes better able to monetize that large number of users.

Plug Power continues its recent run
Shares of the fuel cell maker rose more than 14% early in the session, continuing its recent run.

There hasn't been much news specific to the company to explain Plug Power's rise -- the stock appears to be getting bid up (alongside its fuel cell rivals) as hopeful investors pile into the sector. Electric car maker Tesla's recent success may have spurred interest in the space; in particular, Tesla's announcement of its forthcoming gigafactory may be contributing to Plug Power's recent momentum.

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Sam Mattera has no position in any stocks mentioned. The Motley Fool recommends Facebook. The Motley Fool owns shares of Facebook. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.