Prediction Market Combos: How Prediction Market Parlays Work

Prediction market combos are multi-leg event contracts that resemble parlays at online sportsbooks. In short, they combine multiple predictions into one position, and every leg needs to settle in your favor for the combo to pay.

Combos may look and feel a lot like sports betting parlays, but they’re legally distinct and have functional differences that impact your bottom line. Read on for a thorough but straightforward explainer of how prediction market parlays work, which apps offer the best combos, who determines pricing, and the settlement rules you should know before combining your first contracts.

Best Prediction Market Apps for Combos

We evaluated the major prediction market apps’ parlay offerings on five factors that we personally care about or that other people consistently mention on social media: builder flexibility (custom vs. preset), market variety, fill reliability and liquidity, fees, and the ability to exit positions early.

The following prediction market platforms are all CFTC-regulated, but not one is perfect. That said, some are clearly a league above the others based on our ranking factors. Here’s how they compare and where each could improve (scroll down for full explainers).

App	Strong Points	Weak Points	Download Now
Kalshi	Deepest liquidity and widest market variety; most refined combo builder; no leg limit	Aggressive combo promotion in the sports tab	kalshi.com
Underdog	Only app combining event contracts with fantasy pick’em; also supports standard prediction market combos	Combo entries span two rule sets, which makes settlement harder to predict	underdogsports.com
ProphetX	Zero fees on parlays; wide sports menu; combos may include props and live markets	Sports only; maker margin still built into quoted odds	prophetx.co
Robinhood	Convenient for existing Robinhood users; financial products and prediction combos in one app	Combos support a limited number of sports; hard 10-leg cap	robinhood.com
Polymarket	Strong market variety pedigree from international operations; still in development	Sports-only combos (moneylines, spreads, and totals); feels like a beta product	polymarket.us

Kalshi Combos

Kalshi is the best option for combos for a couple of reasons.

Strengths: First, Kalshi’s market leader status makes it the most liquid platform for combos. Because it has so many users who provide liquidity in a wide range of markets, Kalshi can reliably support a broader range of combo types across various topics.

Secondly, Kalshi’s combo tools and options are the most developed. As a market leader and early mover in offering combos, Kalshi has both technical experience and financial resources to continually test and refine its combo offerings.

As a result, Kalshi’s combos are more customizable, deeper (i.e., liquid), and wider (i.e., varied) than anywhere else.

Notably, Kalshi does not limit the number of legs users can include in combos. The only real limit is whether someone’s willing to take the other side.

A combo of any size can fill if a market maker is willing to quote it. However, liquidity thins quickly beyond three or four legs, so the theoretical flexibility and realistic fill window are two different things. That said, traders have filled combos running well past 20 legs (documented not just on social media, but also on Kalshi’s own featured combos at times).

Weaknesses: Kalshi’s most notable weakness is its incessant promotion of combos inside the sports tab. The “Popular Combos” recommendations go beyond annoying; some of them are ridiculous.

For a company that has stressed its legitimacy as a regulated derivatives product distinct from gambling in courtrooms nationwide, Kalshi is awfully cavalier about pushing 20+ leg combos on its app.

Underdog Combo Entries and Prediction Parlays

The Underdog Sports app offers combos sourced from Kalshi, but Underdog is not just repackaging and reselling someone else’s product. Instead, Underdog adds its own twist to create combo options that don’t exist anywhere else.

Underdog offers two distinct parlay-style features:

• Combo Entry: Combines prediction market contracts with fantasy pick’em selections in a single lineup. For example, a combo entry might pair a Kalshi-powered “Yes” contract on the Broncos winning their Monday Night Football game with two over/under pick’em selections on whether specific players will beat their projected stat totals.
• Prediction Parlay: A standard prediction market combo consisting of event contracts only. Underdog supports multi-game and same-game combinations.

Strengths: Underdog’s primary advantage is the unique product mix. It’s the only legitimate CFTC-registered prediction app that allows users to combine prediction market contracts with fantasy pick’em games. If you’re primarily interested in sports, Underdog is worth considering because it offers both products side-by-side in a single app.

Weaknesses: Underdog’s weak point is complexity at settlement. A combo entry spans two different rule sets, with the fantasy legs graded according to Underdog’s pick’em rules and the contract legs settled under exchange contract terms.

ProphetX Parlays

You can build custom parlays at ProphetX by selecting your legs and desired stake, which sends out a request for quotes (RFQ). Multiple market makers compete to return the best odds, and ProphetX displays the estimated return before you confirm the trade.

The ProphetX app supports multi-game and same-game parlays spanning a wide selection of sports (including major US leagues, college sports, soccer, golf, tennis, and combat sports), with player props and live markets available as legs.

Strengths: ProphetX takes a different approach than most other prediction markets by focusing purely on sports, but its real differentiator is taking no fees on parlays whatsoever instead of its usual 2% fee on net winnings.

Weaknesses: ProphetX focuses solely on sports, so if you want to build combos that include legs from other markets (e.g., politics, economic indicators, etc.), you’ll want to look elsewhere.

It’s also worth noting that “no fees” does not equal “free” because market makers build a margin into their odds when responding to RFQs. That said, the zero-commission model is still a genuine edge over other prediction market apps that charge a commission and send requests to makers who build margins into their odds.

Robinhood Combos

Robinhood is the Kalshi Lite of prediction market parlays. The Robinhood app sources its prediction markets from Kalshi, so it offers a similar range of contract trading options except for a significantly lighter combos menu.

Strengths: Robinhood is an attractive choice if you already have an account there or plan to use its other financial products and want everything in one place.

Weaknesses: Robinhood’s combos represent just a narrow slice of what Kalshi offers, so if you want combos with fewer limitations and for more sports, Kalshi is the way to go.

Currently, Robinhood only supports combos for NFL and NBA markets, and there’s a hard limit of 10 legs per combo. Robinhood offers preset and custom combos, which can span game outcomes, individual player predictions, and more in a single trade.

Robinhood execs have discussed expanding combos to new event categories, but they haven’t named a specific timeline for that. The 10-leg limit is a limitation Kalshi’s combo builder doesn’t have, which is surprising given that Robinhood sources its event contracts from Kalshi.

Polymarket Combos

Polymarket allows traders to build combos directly from any eligible market page, and positions can be sold before resolution like any other position. Pricing runs through a request for quotes (RFQ) system in which market makers compete on quotes.

Strengths: The Polymarket app is still a work in progress, so its strong points are primarily aspirational right now. Polymarket has extensive prediction market experience thanks to its international operations and has earned a reputation for offering a vast array of market categories. Eventually, Polymarket will be a legit competitor when it comes to combos.

Weaknesses: Polymarket’s combo offering still feels like a beta-testing product: sports only, no player props in combos, and early users reported fill failures during the World Cup launch window. Polymarket also offers pre-built parlay-style markets that traders can buy but not customize.

Polymarket’s offerings are still limited at this time: combos are available on sports markets only (moneylines, spreads, and totals), with more market types promised later. A grayed-out combo button means no market maker is currently willing to fill the order, and Polymarket’s suggested fixes are removing a leg, reducing trade size, or waiting.

How Prediction Market Parlays Work

Combos are the prediction market equivalent of sports betting parlays. In short, a combo is a single trade that depends on multiple underlying event outcomes.

Whereas a standard prediction market asks one question, such as whether Team X will win its game, a combo combines multiple questions into one all-or-nothing position.

For example, a sports prediction market combo may require three outcomes to occur:

• Team A to win
• Team B to cover the spread
• Game C to go over the total

If all three outcomes settle correctly, the combo pays $1.00 per contract. If any leg loses, the whole combo settles at $0 per contract.

The similarities to sports betting parlays are obvious, but the underlying mechanics differ in ways that affect pricing, payouts, and what happens when a game goes sideways, or an athlete does not play.

Every Combo Is One Event Contract

Each combo is its own event contract with its own market. When you buy a combo, you’re trading with another market participant, so the contract price is constantly changing as events unfold and sentiment shifts, right up until settlement.

You can close your position at any time by selling your contracts to other traders at the current price, but only if there’s enough liquidity. The amount of liquidity varies depending on how many people use the exchange and the type of combo you’re wanting to trade:

• If you buy into a preset or “recommended” combo on a popular prediction markets app, there will probably be enough liquidity to support trading in and out of the position until the final few minutes.
• If you build a custom 13-leg combo, there’s a good chance you’ll be committed to that position until settlement because fewer people will be interested in your highly-specific, low-probability position.

How Prediction Markets Determine Combo Prices

Most prediction market platforms price combos through a request-for-quote (RFQ) system that responds with a price within seconds:

• You select each leg in your app’s combo builder and submit the combination.
• The platform broadcasts the request to market makers, who compete to price the other side.
• The app returns the best quote for you to accept or decline.

The RFQ model exists because a custom combo is a brand-new market with no trading history. Someone has to price it on demand, and that someone is typically an institutional market maker with correlation models and real-time data.

Unlike sports betting parlays, you don’t get guaranteed execution with prediction market combos. If no participant quotes your requested combination, the order does not fill.

Combo Settlement Rules

Each leg in a combo settles according to the rules of its underlying market, which is what you would expect and makes it possible to avoid any surprises as long as you take the time to read each leg’s resolution rules.

The full combo settles only after every leg has settled, and some prediction market apps run an additional review of the combined position before paying. In most cases, that means the funds arrive within a few hours of the final leg resolving (usually much faster).

Combo DNP Rules

When an athlete in a sportsbook parlay scratches, most betting sites void that leg and recalculate the parlay at the remaining legs’ odds. In other words, a four-leg parlay becomes a three-leg parlay. That makes sense, and it’s easy to follow.

Prediction market parlays work differently and are less intuitive in some respects. Most notably, prediction market apps do not void individual legs or refund whole combos. Instead, each leg settles according to the underlying market’s rules. In most cases, it resolves to its last traded price, and the combo pays the product of the remaining legs’ prices.

For example, imagine you have a three-leg combo of player props. One athlete is ruled out before the game, and that leg settles at $0.70, its last traded price. The other two legs win and settle at $1.00 each. In this case, the combo would pay $0.70 per contract ($0.70 x $1.00 x $1.00).

The rules can vary by platform and even by market, so make sure you confirm how each leg’s underlying market handles DNPs, postponements, and injuries before committing significant funds to a combo.

Selling Before Settlement

Combos are tradeable contracts, so you’re not necessarily locked in until every underlying market has resolved. If there’s enough liquidity (active traders) in your combo’s market, you can sell the position early to lock in a profit or cut your losses.

However, liquidity is not guaranteed. Custom combos are thinly traded by nature, and a position with no willing buyers will ride to settlement whether you like it or not. The more legs and the more obscure markets in your combo, the less likely an early exit will be available at a reasonable price.

How to Check Whether a Combo Quote Is Fair

The single most useful habit in combo trading takes about thirty seconds because every leg has a visible market price, and the fair value of a non-correlated combo is simply the product of those prices. This is a quick calculation that you should run on every quote before accepting.

For example, imagine requesting a three-leg combo where the individual contracts are trading at $0.60, $0.55, and $0.50. Multiply those prices (0.60 x 0.55 x 0.50), and you get a fair value of 16.5 cents.

If you receive a quote of $0.14, you’re getting a discount. If you receive a quote of $0.19, the market maker is charging roughly 15% over fair value, and you’d be better off either buying the three legs individually or skipping the trade.

Keep in mind that correlation complicates the pricing logic. Positively correlated legs (e.g., Team A to win paired with Team A’s quarterback exceeding his projected passing total) deserve a combo price higher than what you’d get by multiplying the individual components because correlated legs tend to rise and fall together.

Trading Prediction Market Combos Responsibly

Combos are a low-probability, high-variance product, which is exactly what makes them engaging. You may know conceptually that they’re risky, but consider this: a four-leg combo of coin-flips wins just 6% of the time.

So, keep your position sizes significantly smaller with combos than you do with standalone contracts. Know that the occasional massive payout won’t cover the fees and margins you’ll pay over the long run and expect massive swings in the short term.

Every CFTC-regulated platform on this page offers deposit limits, and most offer other responsible trading tools like session time limits, temporary timeouts, and permanent self-exclusion.

Even though prediction markets are regulated as financial products, you can call, text, or chat live with the National Council on Problem Gambling for assistance. Anti-gambling software like Gamban and BetBlocker also enable users to restrict access to prediction markets.

Prediction Market Combos FAQ