Prediction markets: how they took off, and how affiliate sites send them traffic

What is a prediction market?

A prediction market is an exchange where people trade contracts on whether something will happen. A contract pays out a fixed amount if the answer is yes, and nothing if it is no, so its price works as a running estimate of the probability. Markets cover economics, politics, culture and, increasingly, sport. The two biggest platforms are Kalshi, a US exchange regulated by the Commodity Futures Trading Commission (CFTC), and Polymarket, which runs an international crypto-based platform alongside its US product.

How fast are prediction markets growing?

Very fast, and sport is the engine. Pew Research Center found that combined monthly volume on Kalshi and Polymarket rose from less than $5 billion in September 2025 to about $24 billion in April 2026. It then more than doubled from $26 billion in May to $53 billion in July, with sports trading during the FIFA World Cup topping $58 billion on Kalshi and nearing $22 billion on Polymarket across June and July.

Analysts expect more. Bernstein estimated $51 billion of prediction market volume in 2025, forecast around $240 billion for 2026 and roughly $1 trillion a year by 2030. CryptoRank data reported by Yahoo Finance put third quarter 2026 volume at a record $188 billion. For the current NFL season, Eilers and Krejcik Gaming expects prediction markets to take the equivalent of $8.4 billion in NFL wagering, or a 21% share of the combined legal market. Volume figures are not directly comparable with sportsbook handle, but the direction is clear.

Why is the legal position so contested?

Because prediction markets look like finance to federal regulators and like betting to many states. In March 2026 the CFTC issued an advisory signalling that sports event contracts can be listed on federally regulated exchanges if they meet its rules, and opened a consultation on the wider framework. States have pushed back hard:

• In August 2026 the Ninth Circuit ruled against Kalshi and Crypto.com, finding that sports-related event contracts are not a federally regulated derivative and that Nevada could act against them.
• Ohio has sent cease-and-desist letters to Polymarket, Robinhood and eight other operators over sports contracts.
• The NFL has filed a brief urging the Supreme Court to hear New Jersey's case against Kalshi, arguing that some contracts threaten the integrity of sporting events.
• Minnesota passed a law that would make it a felony to advertise or market products that promote prediction market transactions, although a federal judge has paused enforcement.

For affiliates, the last point matters most. Rules aimed at advertising and "supportive services" reach publishers and creators, not just platforms.

How do affiliate sites send traffic to prediction markets?

Through the same playbook that built US sports betting, adapted to tighter channels. Four routes do most of the work.

1. Promo code content around big games

Sports publishers write around high-attention fixtures and attach a new-user offer. Covers, for example, runs daily pages for a Polymarket referral code that offers a $25 trading bonus for a $10 deposit and a qualifying trade. These pages rank for branded searches such as "promo code" and "referral code", and they convert readers who have already decided to sign up.

2. Referral and revenue share programmes

The commercial terms are thinner than sportsbook CPA deals. Kalshi's referral offers are only available to eligible US users, and a code must be added within 72 hours of creating an account. Polymarket pays referrers 10% of net fees from direct referrals and 5% from indirect ones, but only once the referrer has $10,000 in lifetime trading volume, and only for the first 30 days of each referral. That pushes serious publishers towards negotiated partnerships rather than self-serve links.

3. Comparison and data sites

Comparison is moving from bonuses to prices. Genius Sports has launched Prediction.com, which lets users compare equivalent event contracts across platforms and follow how probabilities change. Expect affiliates to compete on live odds, price comparison and market explainers, which is useful content that also earns links and citations.

4. Creators and social

Creators have been central, and the platforms are tightening up. After X updated its paid partnerships policy to restrict promotions tied to gambling content, Kalshi removed all affiliate badges from accounts on X, saying the programme had become too difficult to police. Undisclosed promotion is now a suspension risk, so creator programmes need clear disclosure and written briefs.

Why is paid search mostly closed to affiliates?

Google's prediction markets advertising policy only allows certified, licensed providers to advertise, and the only approved location is the United States, excluding Nevada. The same policy lists affiliate sites with related content or broker reviews among the things that can lead to disapproval. In practice, affiliates have to win this traffic through organic search, social, email and partnerships, which makes SEO and content quality the main competitive edge.

What does this mean in the UK?

The UK is a different market with clearer lines. The Gambling Commission says current prediction market products would appear to fall within the definition of a betting intermediary, the same category as a betting exchange, and that unlicensed operators should not target or transact with consumers in Great Britain. The FCA's perimeter report adds that financial prediction market products it has seen are binary options, which remain banned for retail consumers. The FCA has reportedly held talks about easing that ban, but no rule has changed.

For UK affiliates, two rules follow. First, section 330 of the Gambling Act 2005 makes it an offence to advertise unlawful gambling, so promoting unlicensed platforms to British readers is off the table. Second, anything promoting licensed gambling falls under the CAP Code gambling rules, and the ASA holds the operator primarily responsible for its affiliates. The opportunity in Britain is with licensed betting exchanges and with publishers that build trusted, explanatory content ready for any future change.

What should affiliates and operators do now?

• Map the rules by market. Build a live matrix of where each platform and contract type can be promoted, by US state and by country, and geo-gate pages and links to match.
• Lead with explanation, not just codes. Most people still do not understand how event contracts work. Clear explainers, worked examples and risk information rank well, earn AI citations and support compliance.
• Disclose everything. Label creator content and affiliate links clearly upfront, in line with the ASA's rules on recognising ads and each platform's paid partnership policy.
• Own the audience. With paid search closed and social policies shifting, email lists, communities and podcasts give affiliates a channel no platform can switch off.
• Measure quality, not clicks. Referral terms reward funded, active traders, so track verified sign-ups, first trades and retention, not raw traffic.
• Plan for safer gambling. Sports contracts attract the same audiences as sports betting, so age gating, responsible messaging and clear terms protect both users and partners.

Our guide to GEO and AEO for iGaming affiliates covers how to build content that AI search will cite, and our post on influencer and affiliate compliance sets out the UK labelling rules in detail.