Media giant Viacom Inc. (VIAB), the owner of CBS and MTV, reported a net loss of $18.4 billion for the fourth quarter Thursday due to charges to write down the value of its holdings in radio stations and outdoor advertising.

But its results excluding one-time items beat Wall Street's forecasts.

The net loss, which was equivalent to $10.99 per share, compared with a smaller loss of $385.4 million, or 22 cents a share, in the comparable period a year ago.

Revenues rose 6 percent to $6.3 billion from $5.95 billion last year, led by gains in its cable networks unit, which includes MTV, VH1 and Nickelodeon.

Excluding the effect of the accounting charge and another one-time effect from a tax benefit, the company's earnings from continuing operations rose 22 percent to $714 million or 42 cents per share, beating analysts estimates of 38 cents per share.

Viacom's CEO Sumner Redstone (search) said in a statement that the company had written down the value of its radio and outdoor holdings by $18 billion "to reflect emerging business trends and the competitive environment," and would now "increase our investment and re-evaluate our portfolio in radio."

Radio remains a profitable area of business for Viacom, but its growth has been stunted in recent years, and the company has said it intends to trim down its portfolio of radio holdings to focus on higher-profit stations. Revenues from radio were flat in the latest quarter, and revenues from outdoor advertising rose 9 percent.

Excluding the write-down charge, Viacom's earnings from radio fell 6 percent in the latest quarter, which the company attributed to higher expenses for talent and employees as well as sports rights. The division's profit margins, while still high compared to other businesses, declined to 44 percent from 46 percent a year ago.

Radio's business is being challenged by a number of factors, including the rapid growth of the iPod and other portable listening devices; consumers tiring of advertising clutter; and the emerging challenge of commercial-free radio from paid subscription services like Sirius Satellite Radio Inc. (SIRI) and XM Satellite Radio Holdings Inc. (XMSR).

Other parts of Viacom fared better. Cable networks reported a 9 percent gain in profit on a 15 percent increase in revenues, while earnings from television — essentially the CBS and UPN networks and a group of TV stations — rose 22 percent on a 5 percent gain in revenues.

For the coming year, the company said it expects revenues to grow in the mid single digit percentage range, and earnings per share growth in the high single digits.

For the full year, Viacom reported a net loss of $17.46 billion or $10.19 per share, versus earnings of $1.42 billion or 80 cents per share in 2003. Full-year revenues rose 8 percent to $22.53 billion from $20.83 billion.