Comcast Corp. added video customers in its fourth quarter, its first gain in that business in six-and-a-half years.

Comcast has been investing in new products and customer service to morph from a cable company to a technology company, Chairman and CEO Brian Roberts told investors Tuesday at the Citi Internet Media & Telecommunications Conference.

Roberts said that the moves are paying off as Comcast "modestly" grew its base of video customers in its fourth quarter. This follows a decline in video subscribers for 26 straight quarters.

"It will take some time before the entire year will grow but it is a real beginning of an exciting reversal of trends," Roberts said.

Comcast, the nation's largest TV and Internet provider, ended its third quarter with 21.6 million video customers.

Shares of the company increased $1.81, or 3.6 percent, to close at $52.83. The stock fell 2 cents in after-hours trading.