The National Football League season is back in full swing, with thirteen games on tap for the first NFL Sunday. Brands and businesses have already turned on their marketing spigots, including the sports prediction market operators competing for fans' attention and dollars.

DraftKings and FanDuel, which have the largest market shares in the traditional U.S. sports betting market, are ramping up promotions since they launched prediction markets that now allow the companies to operate in all 50 states. Prediction markets Kalshi and Polymarket, meanwhile, need to maintain their leading positions as the space grows crowded.

Those four businesses aren't just competing between themselves. There are a dozen other companies in the mix that have prediction markets: Betr, Coinbase, Crypto.com, Fanatics, Gemini, Novig, OG, PrizePicks, ProphetX, Robinhood, Sleeper, and Underdog.

On Meta's social media platforms, including Facebook, Instagram, and WhatsApp, the number of prediction markets ads has climbed. On Aug. 13, the sixteen prediction markets had 968 individual active ads on the platforms, according to Aldrin Research. As of Saturday, there were 3,010.

At their core, the prediction market platforms aren't that different; they all offer financial contracts that pay out depending on the outcome of a sporting event, like "Will the Philadelphia Eagles beat the Dallas Cowboys?"

The crowded field creates an advertising opportunity worthy of AMC's Mad Men : How do multiple companies selling identical products stand out?

One tried-and-true strategy: a celebrity endorsement.

In the week leading up to NFL Sunday, Polymarket announced LeBron James as an ambassador, then debuted an ad with James and a coterie of other sports and pop-culture celebrities, including Derek Jeter, Eli Manning, and Spike Lee. Polymarket has a data sharing partnership with Dow Jones, the publisher of Barron's.

A Betr ad launched this week reunited Jeremy Piven and Adrien Grenier, the stars of HBO's Entourage. Kalshi is also running an advertisement featuring former NFL player-turned-actor Marshawn Lynch. Not to be outdone, Novig generated a slew of headlines after the sports trading platform revealed its not-safe-for-work ad campaign featuring actress Sydney Sweeney.

These glossy campaigns, meant for television commercials and billboards, are just one front of the prediction market ad war. The majority of promotions are happening on social media-where things are much messier.

In one Betr ad that looks like it was filmed on a cell phone, a distraught bettor sinks to his knees and exclaims, "No dude, no! I lost on PrizePicks again!" The person behind the camera replies, "Dude, I told you to get on Betr."

Multiple social media ads promoting DraftKings have influencers denigrating Kalshi. Another influencer ad promoting Novig highlights how traditional sportsbooks take a cut of winning bets, while prediction markets do not.

Representatives for Betr, PrizePicks, Kalshi, and DraftKings didn't immediately respond to requests for comment.

It's still early days in the ad wars. Of the social media ads that market some kind of promotion for using a prediction market app, 95% of them have offered sign-up bonuses for new users, according to Aldrin.

That shows that prediction markets are focused on onboarding new customers early in the NFL season-and more ads like the one from Betr trying to steal users away from competitors may come later.

How the marketing evolves over the course of the season will signal different strategies from the advertising teams as they prepare for the next battle for new customers.