Snapchat's publisher portal Discover sounded like a good deal for media companies when it launched in January: Media companies can get their content in front of Snapchat's youth-heavy audience and make some money in the process by running ads on their channels. Snapchat claims that 60 million people check out the U.S. and international versions of Discover each month, so the audience appears to be there. But what about the money?

Discover has averaged 2.5 ads a day in total across all 12 Discover channels since July 13, according to data collected by Ad Age. By comparison, over that same 30-day period Discover has averaged 110 stories -- editorial articles, videos or images posted by each publisher to their respective channel -- per day in total across all 12 channels. Publisher-by-publisher breakdowns can be found at the end of this article.

That's one ad for every 44 stories, and it's even fewer advertisers. Eighteen brands -- including Ford, Gatorade, HP, Dick's Sporting Goods, T-Mobile, VH1's "Dating Naked," Marvel Studios' "Ant-Man" and Paramount's "Mission Impossible: Rogue Nation" -- were responsible for the 76 ads that have run on Discover since July 13.

The lack of ads doesn't appear to be due to a lack of audience, though that had been a concern at one point. In April tech news site The Information reported that Discover's traffic had declined by 30% to 50% on average since the portal launched on January 27.

Discover traffic appears to have rebounded since then. Execs at CNN and National Geographic told Ad Age that their channels' viewership numbers have returned to their levels at launch. They declined to provide specific figures but said Snapchat's move last month to feature Discover in its higher-profile Stories tab was proving a major benefit in driving traffic to their channels. One exec at a Discover publisher said that the publisher's channel is now seeing more than 1 million unique viewers a day.

To hear Snapchat and several of the Discover publishers tell it, ad sales had not been a big priority during the first six months that Discover has been on the market. "The first thing we were going for was the audience and the chance to curate and craft and edit stories in a new and interesting way for that audience on that platform," said Meredith Artley, editor-in-chief, CNN Digital. "Then we'll get the revenue later."

"Later" may not be that far away, though, as Snapchat and several Discover publishers look to put more focus on ad sales through the end of the year and to capitalize on the usual fourth-quarter marketer spending spree.

Sarah Baehr, senior VP and digital director at Carat USA, expects that more marketers may open up to running Discover ads in the fourth quarter, when brands often look to take some risks to stand out in the crush of holiday shopping ads. "A lot of the testing Snapchat has been doing is getting to the point where they have a product that makes sense for marketers going into the fourth quarter," she said.

Snapchat's own ad sales team didn't start "actively" selling Discover to advertisers until the end of July and does not sell ads against its own Discover channel, according to a Snapchat spokeswoman. And several Discover publishers that Ad Age contacted said that they already have advertisers in the pipeline for later this year.

CNN has run 10 ad campaigns on its Discover channel since January and will run five more between now and October, according to a spokesman.

"Cosmopolitan and our partners reach an immense audience through Snapchat Discover, and it is a new and meaningful revenue stream for us," said Todd Haskell, senior VP-chief revenue officer at Hearst Magazines Digital Media, in a statement. "We've run 20 marketing programs in the past ten weeks, from a wide range of brands in the fashion and beauty, media (film and television), food and beverage categories, many of whom have re-upped for the fall campaigns after seeing outstanding performance and engagement metrics."

A Vice spokesman said in an email that its Snapchat Discover programming, including culture documentaries and lifestyle shows, had performed "remarkably" and brought millions of new viewers. "We've already signed over ten advertisers to Vice's Discover channel across U.S. and U.K. with ads to run in the coming months," he said.

BuzzFeed hasn't run any ads since joining Discover on July 27, but has advertisers lined up, a spokeswoman said.

IHeartRadio also joined Discover on July 27 but is keeping its channel ad-free until next month. "We have initially launched our Discover Channel ad free to engage users with a clean experience to demonstrate the great breadth of content the channel will feature and also build our stats to show advertisers the power of iHeartRadio on Snapchat," said Carter Brokaw, president of digital revenue strategy at IHeartRadio parent IHeartMedia. "The feedback from users and advertisers has been extremely positive since launch and we have been receiving a lot of incoming interest."

National Geographic's Discover ad sales got off to a relatively slow start, said Chief Media Officer Declan Moore. National Geographic's traditional advertisers -- Mr. Moore cited brands like Canon and Rolex -- aren't the same group that would be interested in Snapchat's audience, and so the organization's sales staff has needed to develop relationships with new advertisers, he said.

It seems to have had some success: National Geographic's Discover Channel has booked advertisers such as Verizon Wireless and films such as "Poltergeist," "Jurassic World" and "San Andreas," and it has deals in place to run ads promoting other films later this year. "The pipeline we have set up as we're going to kick off with the September season and on into Q4 looks very strong," said Mr. Moore.

Part of what has helped National Geographic gin up advertisers' interest is its ability to sell brands more than its Discover channel alone. "It's been really a part of a broader discussion of how we can reach that demo as opposed to specifically here's what we can do just on Snapchat," said Mr. Moore. He added that some of the advertisers waiting in the wings are brands that have previously advertised on National Geographic's other properties and are now interested in its Discover channel. "As I look at the pipeline, it's a 50-50 mix between those we are for sure not carrying on other platforms and those that we do have existing relationships with," he said.

That ability to extend an ad buy beyond Discover could pique more marketers' interests. "From what I originally saw, publishers appeared to be selling it like a one-off," said Ms. Baehr. "For many of these publishers, this offering is one part of how they can reach their audience, and so thinking about how Snapchat fits into their overall proposition is something they've been working through as well."

That cross-platform ad sales strategy has also been adopted by ESPN, according to a spokeswoman. She declined to comment further on the network's Discover ad sales strategy.

Comedy Central echoed CNN's take-it-easy strategy to start off. "As with anything new, we made the strategic decision to introduce advertising into our channel slowly, to allow us to learn as we went, and we couldn't be more pleased with how successful the ads have been for our partners, as well as how well-received they have been by our Snapchatter fans," a Comedy Central spokeswoman wrote in an email.

Representatives at Daily Mail, Food Network, People, Warner Music Group and Yahoo either declined to comment or did not respond to requests for comment.