* 4th-qtr adj EPS $1.21 vs Wall Street view $1.17
* Revenue of $3.36 bln, about in line with forecast
* Domestic ad revenue falls 6 pct
By Jennifer Saba
Nov 15 (Reuters) - Viacom Inc reported a rise in quarterly profit, defying weak box-office sales and a challenging advertising environment.
The company said on Thursday that fiscal fourth-quarter net income rose 12 percent to $643 million even though revenue fell 17 percent.
"At the end of the day, I think they are really focused on operating efficiency," Brian Wieser, an analyst with Pivotal Research Group, said. "It's a company that can still grow its margin even in a weak advertising market."
Viacom's shares rose nearly 3 percent to $49.32 in morning trading.
Investors seemed undaunted by the challenges Viacom faces at some of its most high-profile cable networks, MTV and Nickelodeon, which are in a ratings slump.
Still, Viacom Chief Executive Philippe Dauman worked to reassure analysts that Viacom is looking to right the course.
"It's highly successful," he said, responding to a question about whether MTV was broken.
"Just this past Monday, 'Catfish,' which we premiered at 11 (p.m.) was the highest-rated launch in MTV history. So MTV is very healthy, indeed," he said.
On Monday, Viacom announced Susanne Daniels, known for such hit shows as "Buffy the Vampire Slayer" and "Dawson's Creek," joined MTV as the head of programming.
Producing hit shows and increasing viewership is important to Viacom since it relies partly on advertising revenue, which is closely tied ratings.
Domestic advertising revenue for the fourth quarter fell 6 percent.
Dauman signaled that advertising revenue growth would remain in negative territory this quarter, although sequentially it was expected to improve.
During the quarter, Viacom and satellite pay-TV provider DirecTV Group had a showdown resulting in a bruising 10-day blackout this summer of Viacom's channels on DirecTV. The dispute was over a contract regarding affiliate fees, or the price that cable operators pay to air Viacom's channels. Viacom said it had negotiated higher fees in the new deal.
That helped push up affiliate revenue 12 percent.
The company's filmed entertainment unit, which consists of Paramount Pictures, said revenue fell 39 percent on tough comparisons to last year when the studio released "Transformers: Dark Side of the Moon".
Still, the company managed to increase operating income in that division 5 percent because of TV and digital deals and cost cuts.
For instance Amazon Inc and Hollywood studio partnership Epix, where Viacom is a joint owner, struck a three- year deal to stream movies and TV shows to Amazon's Prime Instant Video subscribers.
For the fourth quarter, total revenue was $3.36 billion, roughly in line with analysts' expectations of $3.40 billion, according to Thomson Reuters I/B/E/S.
Viacom posted adjusted earnings per share of $1.21 compared with analysts' forecast of $1.17.
The company said it plans to purchase $700 million in stock for the quarter ending in December and anticipates buying back $2.5 billion during fiscal 2013.