TV’s annual upfront market has begun to move in earnest, but the networks are ceding some ground to Madison Avenue in the process.

CBS, ABC and NBC have all begun to secure advance advertising commitments as part of the market for commercial time on TV, according to media-buying executives and other people familiar with the pace of negotiations. These executives suggest the three networks are all jockeying for increases in the cost of reaching 1,000 viewers — a measure also known as a CPM that is central to these annual talks — in the range of 2% to 5%.

The numbers suggest the TV networks continue to face pressures from advertisers that are exploring new opportunities to sponsor new kinds of media, including streaming video. For the fourth consecutive year, advertisers are lobbying to narrow the rate of increase they pay, and are, by several accounts, succeeding. In 2014, CBS secured a CPM increase of 6%. ABC pressed for increases of 4% to 5%. And NBC pushed for CPM increases of between 7.5% and 8%. Advertisers committed between $8.17 billion and $8.94 billion for the 2014-15 broadcast primetime schedule, according to Variety estimates.

Fox has already begun doing deals, according to people familiar with the talks, with CPMs staying flat with last year’s terms or rolling back as much as 2%. The network has come under pressure by advertisers to lower its pricing owing to ratings shortfalls it has weathered in recent seasons with the aging of “American Idol.”  Because of its ratings success in past years, Fox has some of the highest rates for reaching 1,000 viewers in the business.

The CW has also begun to make progress in sales, according to a person familiar with the situation, though terms of deals could not be immediately learned.

All of the networks have specific pieces of content and ad innovations to highlight. NBCUniversal is said to be pressing for sales that involve not only its NBC network, but its cable outlets as well. ABC, according to ad buyers, is touting its ratings growth last season. CBS has been calling attention to its 2016 broadcast of Super Bowl 50 as well as the debut of Stephen Colbert in “The Late Show” in September.