CBS, led by Chief Executive Officer Les Moonves, sold about 78 percent of its inventory for the season that starts in September, said the person, who asked not to be named because the numbers are private. Because a slightly lower amount of inventory was sold compared with last year, the total dollar figure was little changed from a year earlier, the person said.

Broadcast and cable networks released their 2012-2013 schedules last month during so-called upfront meetings with advertisers, letting them book advance commitments for the season. The upfront purchases guarantee rates for advertisers that may be lower than what they would get later via what is called the scatter market. Networks, meanwhile, get the assurance of knowing that most of their ad time will be sold.

CBS, based in New York, will add three dramas and one comedy to its schedule next season. The company is adding the fewest new shows of the four main broadcasters, relying instead on its current crop of heavily watched programs.

The new dramas “Elementary,” “Vegas” and “Made in Jersey” and a comedy called “Partners” will air on the network in the TV season starting September, CBS Entertainment President Nina Tassler said last month.

Football Boost

Fueled by the Super Bowl and a key football playoff game in prime time, CBS is poised to draw the most viewers ages 18 to 49 next season for the first time in 20 years. The network, first in total viewers for nine of the last 10 years, will lead its competitors in advance advertising commitments from marketers and ad rates, Moonves said on a May conference call.

CBS is bringing back 19 shows, including “Big Bang Theory,” “Two and a Half Men” and “NCIS,” while canceling “CSI: Miami” after the show had been on the air for 10 years.

CBS was expected to lead the four major networks in advertising commitments, bringing in as much as $2.78 billion, Spencer Wang, an analyst in New York with Credit Suisse Group AG, wrote in a May report.

The stock gained less than 1 percent to $32.46 at the close in New York. CBS shares have advanced 20 percent this year.

CBS’s upfront sales were previously reported by AdAge.