Comcast Corp posted a higher-than-expected quarterly profit as it added Internet and phone subscribers, but its margins were hit by marketing costs as the No. 1 U.S. cable operator fends off competition from phone and satellite companies.

The cable company, whose senior management spent much of the fourth quarter negotiating a deal to buy a 51-percent stake in NBC Universal from General Electric Co, said on Wednesday it changed its strategic focus midway through 2009 to proactively pursue market share.

That translates to lower price increases for customers and greater promotional spending, said Collins Stewart analyst Thomas Eagan. That's why the fourth-quarter customer numbers were better than people expected but some of the financials were worse.

Comcast's fourth-quarter net profit rose to $955 million, or 33 cents a share, from $412 million, or 14 cents a share, a year earlier.

After adjusting for a tax benefit, profit was 29 cents a share. Revenue rose 2.9 percent to $9.07 billion.

Analysts had been expecting profit of 27 cents and revenue of 8.97 billion, according to Thomson Reuters I/B/E/S.

Comcast's EBITDA margin narrowed by 0.3 percentage point to 40.6 percent, but analysts were expecting an increase. Bernstein's Craig Moffett had forecast 41.4 percent.

Comcast, whose shares dipped 0.8 percent, did not give a detailed financial outlook but said capital investments will fall in 2010, even as it expands new services like faster Internet access and all-digital TV.

I like the fact they continue to stress that capex will come down and continue returning cash, said Thomas Villalta, of Jones Villalta Funds, which owns Comcast shares. But there was nothing overly impressive or overly negative about the results.

The company also introduced a new brand, Xfinity, for its video, high-speed Internet and digital phone services. The company has previously used the brand for its online on-demand services.

The brand will start initially in 11 Comcast markets where it has launched all-digital and super-fast Web services.

The strategy is similar to one used by New York-based Cablevision Systems Corp, which uses the Optimum brand for its cable services.

Comcast Chief Executive Brian Roberts said the company will focus on associating the new brand with improved customer service and more choices.

The Philadelphia-based cable company added a net 247,000 high-speed Internet customers and 243,000 digital phone subscribers in the fourth quarter. Kaufman Bros analyst Todd Mitchell had forecast 194,000 new Internet subscribers and 296,000 new phone customers.

Comcast lost more than 199,000 basic video subscribers during the quarter. Mitchell had expected Comcast to lose 151,000 video customers.

He said subscriber growth for cable companies like Comcast and Time Warner Cable Inc are beginning to slow down and investors are now focusing on return of capital through share buybacks and dividend payments.

Comcast shares fell 13 cents to $16.16 in morning trading.

(Reporting by Yinka Adegoke; Editing by Derek Caney)