(Reuters) - Viacom Inc VIAB.O, owner of MTV and Comedy Central, said Thursday it expects lower revenue from cable and satellite companies in 2018, a forecast that sent its shares down almost 10 percent in morning trading.

FILE PHOTO: A woman exits the Viacom Inc. headquarters in New York, U.S. on April 30, 2013. REUTERS/Lucas Jackson/File Photo

The largest U.S. cable and satellite companies have shed more than a million subscribers so far this year, a situation that has left them less willing to pay for Viacom’s programs.

Improving affiliate revenue - the sales Viacom generates from distributors - has been a key focus of Viacom Chief Executive Bob Bakish since he took the helm late last year.

“In the past year, deals representing nearly 50 percent of our subscriber base have been renewed or extended, and we now have no significant renewals until well into 2019,” Bakish said on a call with analysts.

The question is whether future deals will also reprice at the same or lower rates, said Brian Wieser, an analyst at Pivotal Research.

“What is to say that every other distributor won’t reset pricing?” Wieser asked.

Shares of Viacom were down 3.9 percent $23.65 in midday trading on the New York Stock Exchange, after earlier tumbling nearly 10 percent.

Last month, Viacom reached a deal with Charter Communications CHTR.O to put eight of its most popular networks in Charter's cheapest U.S. cable bundle, after Charter had put some channels in its more expensive packages.

The new deal with Charter does not take effect until early next year, which is part of the reason for the expected drop in affiliate sales in 2018, Viacom said.

Viacom said it expects high single-digit declines in U.S. affiliate sales in the first half of 2018. For the year, it expects affiliate sales to be down in the mid-single digits with positive sales returning in 2019.

The New York-based media company said revenue grew 2.9 percent to $3.32 billion, beating analyst estimates, as U.S. advertising sales improved to their strongest since 2014.

Revenue from Viacom’s film unit, which includes theater and licensing revenue, grew 2 percent to $789 million from a year earlier.

Domestic affiliate revenue fell 3 percent to $948 million in the quarter and domestic ad sales were flat at $936 million.

Net profit attributable to Viacom rose to $674 million, or $1.67 per share, in its fiscal fourth quarter ended Sept.30, from $254 million, or 64 cents a share, a year earlier.

The quarter included a $127 million gain from an asset sale.

Excluding items, the company earned 77 cents per share.

Analysts, on average, had expected earnings of 86 cents per share and revenue of $3.23 billion, according to Thomson Reuters I/B/E/S.