Cablevision’s (CVC) first-quarter profits soared thanks to an influx of new subscribers, but the cable giant’s results came in shy of Wall Street’s expectations.

The company said it earned $74.2 million, or 24 cents a share, last quarter, compared with a profit of $21 million, or 7 cents a share, in the year-earlier period. 

Analysts had been projecting significantly stronger EPS of 33 cents.

Revenue rose 5.2% to $1.75 billion, ahead of the Street’s view of $1.73 billion.

“Cablevision had a strong start to 2010. Subscriber increases across all of our consumer services, including basic video, fueled our growth in cable, and continued our industry-leading penetration rates for yet another quarter,” CEO James Dolan said in a statement.

Shares of Cablevision took a hit on the weaker-than-expected profits and as part of a sector decline in the wake of the release of new broadband regulation plans from the Federal Communication Commission. Cablevision's stock slid 6.94% to $24.95 Thursday afternoon, compared to a drop of 4.05% to $18.94 for rival Comcast (CMCSA). 

Cablevision’s telecommunications division, which includes its Optimum video, data and voice services, saw its revenue rise to $1.4 billion last quarter, up from $1.3 billion in the year-ago period. Cablevision added 900 basic video customers, 12,000 digital video customers and 42,600 high-speed data subscribers last quarter. The company’s phone subscribers grew by 42,300, or 2.1% , from the end of 2009.

Cablevision’s Newsday division saw its revenue sink by 10.4% to $74.7 million last quarter as newspapers continue to struggle. Ad revenue slumped 12.7%.