Viacom, the owner of MTV and Paramount Studios, has reported a quarterly loss of $18bn (£9.4bn) after writing down the value of its radio business.
Meryl Streep in Paramount's The Manchurian Candidate
The media giant said it had reduced the book value of its Infinity radio group due to stiffer competition and the growth of advertising-free stations.
It now plans to sell some smaller stations as well as non-core assets, such as movie theatres and theme parks.
Excluding one-off charges, Viacom made a profit of $714m, up 22% on last year.
This result was ahead of market expectations.
Radio remains profitable for Viacom, but revenues were flat in the final quarter as more people turned to commercial free stations and portable music players such as iPods.
Viacom saw a better performance in other areas of its business.
Profits from cable television channels such as MTV and Nickelodeon rose 9% while network television - including CBS - saw a 22% increase in earnings.
For the year as a whole, Viacom recorded a net loss of $17.46bn, on revenues up 8% at $22.53bn.
Analysts said Viacom was now paying the price for costly acquisitions in the past.
"The one thing I hope they have learned is acquisitions are bad for them," Richard Greenfield, an analyst with Fulcrum Global Partners, told Reuters.
"Maybe they should stop buying things."
Viacom's shares were down 1.7% at $35.43 in early trading.