The Dow Jones Industrial Average (DJINDICES:^DJI) had shed 52 points as of 11:30 a.m. EDT. Dow Jones component AT&T (NYSE:T) was outperforming its index, but tech stocks Facebook (NASDAQ:FB) and Pandora (NYSE:P) were experiencing sharp sell-offs.

European data falls short of expectations
There were no major U.S. economic releases of note on Monday. In the absence of U.S. data, investors may have been turning their attention toward Europe, where a number of economic indicators suggested eurozone economic activity may be weaker than anticipated.

While the eurozone's manufacturing purchasing managers' index was reported in line with expectations, its services PMI reading of 52.4 missed the 52.6 estimate. European markets moved lower on the news, and some of that weakness may have carried over to the Dow Jones.

AT&T sees bullish bets
AT&T rose a little less than 1% early in the session. There wasn't any particular news that would affect AT&T's business, but Bloomberg noted a high degree of bullish bets on the stock.

Investors appear to be betting aggressively on AT&T's rise, as a recent multi-month sell-off sent shares of the Dow Jones telecom down nearly 10%.

Pandora hikes subscriber fees
While AT&T shares may have lost more than 9% in the last two months, Pandora shares fell more than that on Monday alone. At one point, shares of the Internet radio giant were down more than 10%. The stock was still down nearly 9% as of 11:30 a.m.

Last week, Pandora announced that it would hike the subscription fee for its Pandora One ad-free service. Citing the rising costs of music, Pandora's rate hike could drive Internet radio fans to one of its many competitors.

Facebook shares stumble
Shares of Facebook were down 4.6% in early trading on Monday. There didn't appear to be any real news affecting Facebook's stock -- no major releases, analyst changes, or anything else of note.

However, shares of the social networking giant have risen more than 30% in just the last six months. Facebook investors may have simply been taking profits early on Monday, causing shares to stumble. 

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Sam Mattera has no position in any stocks mentioned. The Motley Fool recommends Facebook and Pandora Media. The Motley Fool owns shares of Facebook and Pandora Media. 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.