Les Moonves, chief executive with CBS Corp. (CBS), said Thursday sales volume are lower for this year's upfront ad sales season, but he said revenue is flat for the percentage of inventory the company has sold so far.

On a conference call following the company's second-quarter earnings release, Moonves echoed other TV network executives, saying CBS will hold more ad inventory to sell in the so-called scatter market when the new television season begins this fall.

He estimated that CBS will sell roughly 65% of its ad inventory for the fall season in the upfront, while last year it sold between 75% and 80% of its inventory.

Advertisers appear to be holding back some of their spending in hopes of winning price reductions. In turn, networks are holding more inventory than usual in hopes that an economic recovery will spur demand later in the year, allowing them to charge higher prices for ads.

"The upfront will end up being very strong for us, and so will the fall season," Moonves said.

In recent late trading, CBS shares are up 8.4% at $9.25.

-By Nat Worden, Dow Jones Newswires; 212-416-2472; nat.worden@dowjones.com