Oct. 25 (Bloomberg) -- Comcast Corp., the largest U.S. cable-television company, fell the most in five years in Nasdaq trading after adding fewer phone and Internet subscribers than analysts estimated amid a slump in home sales.

Comcast added 523,000 net phone customers and 450,000 high- speed Internet clients in the third quarter, falling short of estimates by Goldman Sachs Group Inc. and Lehman Brothers Holdings Inc. analysts. Declines in the housing market reduced consumer demand, hurting Comcast and other cable-TV providers, said Sanford C. Bernstein & Co. analyst Craig Moffett.

``There's no one metric that's a disaster but neither is there one where they knocked the cover off the ball,'' said Moffett, who has an ``outperform'' rating on the stock and doesn't own any. ``There's no question that housing is having an impact on the sector.''

Third-quarter net income fell 54 percent to $560 million, or 18 cents a share, after year-earlier gains on asset swaps, Philadelphia-based Comcast said today in a statement. Sales rose 21 percent to $7.78 billion.

Comcast shares fell $2.57, or 11 percent, to a 15-month low of $21.28 at 4 p.m. in Nasdaq Stock Market trading. The decline was the biggest since August 2002. The shares have dropped 25 percent this year.

Charter Communications Inc. shares fell 58 cents, or 23 percent, to $1.97. Time Warner Cable shares dropped $2.71, or 8.5 percent to $29.30 in New York Stock Exchange composite trading and Cablevision Systems shares lost $1.42, or 4.6 percent, to $29.40.

`More Competitive'

The company spent $1.5 billion to upgrade systems acquired with last year's purchase of Adelphia Communications and expand digital-cable and phone service. Comcast is trying to grab market share from phone companies AT&T Inc. and Verizon Communications Inc., which started TV service to compete with cable.

Comcast reiterated that sales will rise at least 11 percent in 2007, adding that ``the more competitive environment and less-robust economy may have a slight impact'' on full-year results.

Excluding some gains and costs, third-quarter profit met the average of 19 analyst estimates compiled by Bloomberg.

The year-ago quarterly profit included a $669 million net gain related to the Adelphia transaction, under which Comcast swapped cable assets with Time Warner Inc.

Comcast posted net income of $1.22 billion, or 38 cents a share, in the third quarter of 2006.

Anthony Noto of Goldman Sachs predicted 590,000 new phone and 500,000 new high-speed Internet subscribers for the quarter. He has a ``buy'' rating on the shares and doesn't own any.

Lehman's Vijay Jayant, who has an ``equal weight'' rating on the shares and doesn't own any, projected 675,000 new phone and 500,000 new Internet users.

`Business Challenges'

Comcast signed up 489,000 new digital-cable customers, more than the 398,000 projected by Moffett. Basic cable subscribers fell by 65,000.

``We are realistic about some of the business challenges but nowhere do I see a more fundamentally strong and growing company in the telecom entertainment sector,'' Chief Executive Officer Brian Roberts said on a conference call today.

The company also increased its stock buyback program by $7 billion, bringing the total to as much as $8.2 billion. The company has bought $1.9 billion of its stock so far this year.

AT&T, the biggest U.S. telephone company, said on Oct. 23 that its consumer phone lines fell 4.7 percent to 35.8 million in the third quarter from a year earlier, amid competition from cable providers such as Comcast.

AT&T, also the top seller of broadband Internet service, said it had 126,000 television customers at the end of the third quarter, up from 100,000 at the beginning of September. The company is close to surpassing its forecast for 10,000 installations a week by the end of the year, said Richard Dietz, senior vice president of investor relations.

(Comcast held a conference call at 8:30 a.m. New York time. Please dial +1-800-642-1687 and enter passcode 18381176 to access a replay of the call.)

To contact the reporter on this story: Gillian Wee in New York at gwee3@bloomberg.net.

Last Updated: October 25, 2007 16:07 EDT