Prediction Market Apps: What They Are and How They Work

A prediction market is a marketplace where participants buy and sell contracts tied to the outcome of future events. The price of each contract reflects the market’s collective assessment of how likely that event is to occur. A contract trading at $0.65 implies a 65% probability. The model aggregates information from many participants, often beating expert forecasts, because money on the line creates a strong incentive for honest, researched predictions. Prices update in real time as new information enters the market. That structure puts prediction markets in an uneasy relationship with gambling law. When the underlying event is a sporting contest or an election, the experience of buying a contract is difficult to distinguish from placing a bet, and regulators in seven states have said exactly that. The platforms respond that they are federally regulated financial exchanges, not sportsbooks, and that the legal rules governing derivatives markets, not state gambling statutes, control what they can offer and to whom. That dispute is now being resolved in federal courts across the country, with no clear winner yet.

The Major Platforms

The leading platforms fall into three broad categories. Polymarket is the largest by historical volume, crypto-based and global, trading in USDC stablecoin with no native mobile app. Kalshi is the first CFTC-approved US exchange for event contracts, with a native mobile app and coverage spanning elections, Federal Reserve rate decisions, weather and entertainment. Manifold is a free, play-money platform using virtual currency, an ideal starting point for anyone who wants to learn the mechanics without financial risk. PredictIt is research-oriented, academically affiliated and CFTC-permitted, with an $850 per-market cap focused on US political questions.

How They Work

When a question is listed, the platform creates two binary contracts: one that pays $1 if the event occurs and one that pays $1 if it does not. Traders buy and sell those contracts at prices between zero and one dollar. If you believe the probability of an event is higher than the current market price implies, you buy the “yes” contract. If you think the market is overestimating the odds, you buy “no.” You can exit your position at any time by selling to another trader at the current market price. When the event resolves, every winning contract pays out $1 and every losing contract pays out zero.

The price at any moment reflects what the collective market believes the probability to be. If a contract for “Republicans hold the Senate after the 2026 midterms” is trading at $0.58, the market is saying there is a 58% chance that happens. As news breaks, polls shift and candidates stumble, traders update their views and the price moves accordingly. Unlike a poll, which captures a snapshot, a prediction market price is a living number that changes every time someone is willing to put money behind a different view.

How This Compares to Gambling

The comparison to gambling is both obvious and genuinely contested. On the surface, both involve risking money on an uncertain outcome, but the mechanics differ in important ways. In sports betting, you place a wager with a bookmaker who sets the odds and takes a cut regardless of the outcome, known as the vig. The house always has an edge. In a prediction market, you are trading with other participants on an exchange, the same basic structure as a stock market. There is no inherent house edge on the contract itself, and the platform earns fees on transactions rather than taking the other side of your bet. A traditional wager is also locked in once placed, while a prediction market position can be sold at any time. If you buy a “yes” contract at $0.40 and the price moves to $0.70 as sentiment shifts in your favor, you can sell and pocket the gain without waiting for the event to resolve.

What blurs the line is the subject matter. When the underlying event is a football game or a political race, the functional experience is difficult to distinguish from betting. Maryland regulators made exactly this argument in their cease-and-desist letter to Kalshi, writing that the purchase of a prediction market contract is indistinguishable from placing a sports wager. Prediction market operators counter that the regulatory structure, CFTC oversight of a derivatives exchange rather than a state gaming license, is the controlling distinction. Courts are now being asked to decide which view is correct, and the answer will determine the future of the entire industry.

The Track Record

The performance record, at least, is strong. During the 2024 election cycle, Polymarket called state-by-state results more accurately than most polls. Markets as a class consistently outperform individual expert forecasts on verifiable events, achieving a 76% accuracy rate across measured predictions. Polymarket alone exceeded $1 billion in monthly volume during peak 2024 political season. Known limitations include thin liquidity on obscure questions, which can distort prices, and elevated manipulation risk when contract values are high and trading volume is low. The track record is persuasive enough that the industry has attracted serious capital, mainstream financial partners and, inevitably, serious regulatory attention.

What Is Happening Now

The industry has grown dramatically. In April 2026, Kalshi posted $5.4 billion in taker volume against Polymarket’s $1.99 billion, with the sector total reaching $8.6 billion and open interest topping $1.1 billion. Robinhood’s prediction markets hub, powered by Kalshi, became its fastest-ever growing product, logging 11 billion contracts and more than one million customers in 2025. Coinbase joined the Kalshi partnership in January 2026. New entrants including Hyperliquid, Gemini and DraftKings are now pressing the established players, and the FIFA World Cup 2026 has already become Polymarket’s second-largest market ever at $884 million in lifetime volume.

That growth has brought scrutiny in equal measure. The US Senate passed a unanimous resolution on April 30, 2026 barring senators and all staff from trading on any prediction market, after reports that campaign staffers routinely used unreleased poll data to trade on their own candidates’ prospects. An Army soldier was charged for using classified intelligence to net approximately $400,000 on Polymarket. Kalshi fined and suspended three candidates who had bet on their own races. Senators Todd Young and Elissa Slotkin introduced bipartisan legislation to ban all federal officials and employees from using insider information to make prediction market bets. The insider trading problem is not incidental to prediction markets. It is structural. The more valuable the information embedded in a contract price, the greater the incentive to obtain that information by improper means.

The Legal Fault Line

The underlying legal conflict runs deeper than any single scandal. Prediction market platforms claim that CFTC approval as Designated Contract Markets preempts state gambling restrictions and allows nationwide operation even where betting is otherwise banned. Seven states, including Nevada, Arizona, Maryland, New Jersey, New York, Illinois, Ohio and Connecticut, have sent cease-and-desist letters or filed enforcement actions. Courts have split: a federal judge in Nevada and a federal judge in New Jersey each ruled in Kalshi’s favor on preliminary injunctions, while a Maryland court denied Kalshi’s request, citing a strong presumption against preemption and the state’s traditional authority to regulate gambling. A coalition of 34 state attorneys general has filed briefs arguing that Congress did not silently override state gambling law when it enacted the Commodity Exchange Act. The outcome, possibly at the Supreme Court, will determine whether prediction markets can legally operate everywhere or must comply with the state-by-state framework established after the Court’s 2018 decision in Murphy v. NCAA.

Getting Started

For anyone wanting to engage with prediction markets while the legal landscape sorts itself out, Manifold is the right place to start. It is free, carries no financial risk and is available on any device. Once you understand the mechanics, Kalshi is CFTC-regulated, requires US ID verification and accepts deposits as low as $10. Follow markets where you have genuine knowledge or strong views, and track whether your 70% confident predictions come true 70% of the time. Calibration is what separates serious forecasters from gamblers.

The distinction between gambling and financial prediction remains fundamentally contested. The courts will decide. In the meantime, the apps are live, the contracts are trading and the stakes, legal and financial, keep rising.