Kalshi vs. Polymarket: Full Comparison and Key Differences

Kalshi and Polymarket sit at the top of the prediction market space, but they were built on entirely different foundations. Together they’re processing billions of dollars a week but these apps are not the same.

Much of the confusion is in Polymarket running two separate prediction markets under the same brand. Most of the coverage around Polymarket doesn’t distinguish between the two. The main Polymarket brand you see in the news is related to thes the offshore. Polymarket US, which is in beta is a separate US product registered with the CFTC.

This Kalshi vs. Polymarket comparison provides an overview of all three and distinctly calls out the key differences. Kalshi and Polymarket US are both operating in the US. Polymarket is not.

Below, you’ll find direct comparisons of fees, markets, rules, features and markets and how the US prediction market scene is vastly different from the international.

Unless explicitly noted as Polymarket US, Polymarket will refer to the international version of the site which does not accept US traders.

What each platform is

What is Kalshi?

Kalshi was the first prediction market platform to win federal approval to run event contracts as derivatives — not gambling products. That designation, granted by the CFTC in 2020, is what lets it operate legally in states where sports betting is still banned and why its contracts survive court challenges that would have shut down an unlicensed competitor.

Kalshi runs an order book across the US, allowing you to trade against other traders, not the house. Market availability ranges from economics to financial to sports. Sports contracts are currently geofenced in Massachusetts following a January 2026 preliminary injunction, with that litigation ongoing.

Learn more: Detailed Kalshi review

What is Polymarket?

Polymarket is a decentralized prediction market built on the Polygon blockchain where users trade on the outcomes of real-world events using USDC. There is no house — prices are set by traders buying and selling yes/no shares, with each contract paying $1 to the winning side on resolution.

Because it operates as a decentralized protocol outside US jurisdiction, Polymarket can and does list markets that regulated US exchanges cannot: war, assassination, geopolitics, crypto, culture, and long-tail global events that would never clear CFTC review. These markets are NOT accessible to US residents.

What is Polymarket US?

Polymarket spent $112 million last July to buy a CFTC license outright, acquiring QCEX, a registered exchange and clearinghouse. The CFTC issued its Amended Order of Designation on November 25, 2025 and Polymarket announced a beta launch in January 2026 with sports markets only. The site has yet to fully roll out to the US market and has a large backlog of waiting customers.

Learn more: Detailed Polymarket review

Market coverage

Kalshi lists over 350,000 active markets across sports, politics, economics, and crypto. Sports now accounts for roughly 90% of its trading volume, a shift that accelerated sharply with the 2025–26 NFL season.

Beyond game outcomes, Kalshi offers spread contracts, totals, player props, and a parlay-equivalent feature called Build Your Combo. Its political and economics markets — Fed decisions, CPI, inflation, elections — remain active but are secondary to sports in terms of raw volume.

Kalshi launched mention markets in fall 2025, which let users trade on whether specific words or phrases will appear in speeches, press conferences, or social media posts. These have since grown to volumes comparable to smaller sporting events. Trump mention markets have become increasingly popular across both platforms.

Polymarket’s category mix is genuinely distributed, with roughly 60% of volume coming from outside sports — politics, geopolitics, crypto, and long-tail global events all pull meaningful share.

Polymarket US launched with sports only and remains gated behind a waitlist. Hundreds of thousands of users are still waiting for access as of early 2026, with the company rolling out invites in batches but providing no public timeline for a full launch or expanded category range. Market coverage is limited to a handful of sports.

Volume and liquidity

The numbers are hard to contextualize. Kalshi and Polymarket currently split the market roughly 53/47, with Polymarket US accounting for a fraction of a percent as it continues its beta rollout. For current figures, our prediction markets tracker updates hourly.

Combined, Kalshi and Polymarket produced $1.63 billion across Super Bowl 60 markets — the largest event window in prediction market history, with Super Bowl Sunday alone generating approximately $1.34 billion, the single largest trading day on record. The DeFi Rate tracker reflects rolling figures across all three platforms.

Liquidity is not evenly distributed, and the category snapshot below makes the contrast hard to ignore. On Kalshi, sports pulled $127.1M — roughly 84% of all volume — while crypto ($15.9M), politics ($3.7M), and economics ($1.7M) accounted for the tail. Institutional-sized orders are absorbable in top sports markets; thinner categories carry meaningfully less depth.

On Polymarket, no single category dominates. Sports led at $129.8M (~40%), but misc contracts added $67.3M (21%), politics $48.7M (15%), and crypto $39.6M (12%). Economics contributed another $21.2M.

Polymarket also offers minute markets — short-duration contracts, primarily on crypto prices, that resolve within 15 minutes. These carry a small taker-only fee introduced in early 2026, making them the only markets on the global platform where fees apply. Most standard markets remain zero-fee. Smaller markets on both platforms carry thinner order books, which affects how easily large positions can be entered or exited.

Fees

Kalshi’s fee formula is: 0.07 × contracts × price × (1 − price), capped at $1.75 per 100 contracts for takers and $0.44 for makers. Because price appears as P × (1-P) in the formula, fees are highest on contracts priced near $0.50 and lowest near the extremes.

Polymarket has operated with zero trading fees since inception, with small taker-only fees introduced on 15-minute crypto markets in early 2026 as a deterrent to bot activity. Polymarket US charges a flat 0.10% taker-only fee on total contract value — lower than any competing regulated US exchange. For a full breakdown of how fees compare across platforms, see our prediction market fees guide.

Currency and deposits

Kalshi is a dollar-in, dollar-out platform. Funding options include bank transfer, wire, debit card, Apple Pay, and crypto (BTC, SOL, USDC, WLD). Any crypto deposited through partner ZeroHash is converted to USD upon arrival — your balance and all open positions are held in dollars. Debit card and Apple Pay deposits carry a 2% fee. Bank and wire transfers are free.

Polymarket operates entirely on crypto rails. Both the global platform and Polymarket US require USDC and a connected compatible wallet. There is no fiat deposit option on either version. For users coming from traditional banking, this is a meaningful barrier — funding a Polymarket account involves acquiring USDC through an exchange or on-ramp service before any trading can begin.

Payouts and withdrawals

Kalshi contracts typically settle within a few hours of an event resolving — sports markets often resolve faster, while complex political markets requiring manual verification can take longer. Winnings land in your cash balance in USD and can be withdrawn by ACH, debit card, or crypto. The hold structure is worth noting: debit card deposits are held for three days before withdrawal is available, bank transfers for seven days if withdrawing to the same bank, and 30 days if withdrawing to a different bank.

Polymarket settlement is instant once a market resolves. Winning USDC moves back to your wallet on-chain with no platform withdrawal fee, though standard network fees apply. Getting those funds to a bank account requires an additional step through an off-ramp exchange, as Polymarket does not handle fiat conversions directly.

Interest on balance

Kalshi pays 3.75–4% APY on your total balance, including funds tied up in open positions. Interest accrues daily based on end-of-day portfolio value and pays out monthly. A minimum balance of $250 is required to qualify. The rate is variable and subject to change.

Neither version of Polymarket pays interest on held balances. Your USDC earns nothing while it sits in a connected wallet waiting to be deployed.

Position limits

Kalshi allows positions up to $7 million per market on select high-profile markets — the default limit on most markets is $25,000, with Eligible Contract Participants able to access higher thresholds. In top-tier markets, the limit is sufficient for institutional-sized positions.

Polymarket imposes no fixed position caps. Your practical limit is determined by available liquidity in the market you’re trading. In deep markets, this can support very large positions. In thin markets, it creates meaningful slippage risk.

Resolution

Kalshi designates specific third-party sources in the rules of each contract — for a pro football championship market, that might be AP, Fox Sports, and ESPN. If those sources confirm an outcome, the contract settles. Traders can review the exact sources and settlement logic before placing a trade, and Kalshi’s oversight means disputes go through a regulated process.

Polymarket resolves markets through independent on-chain oracles that verify outcomes using publicly available data. The decentralized model means no single entity controls resolution, but disputes play out through community and oracle governance rather than a regulatory framework. The oracle model means resolution is transparent and auditable by anyone; the Kalshi model means resolution authority sits with a regulated exchange that has accountability to the CFTC.

Regulatory status

Kalshi holds full DCM designation from the CFTC — the same regulatory classification as traditional commodity exchanges like the CME. That status means its event contracts are classified as derivatives, not gambling, which is why Kalshi operates legally in states where sports betting isn’t legal. Federal courts have consistently upheld this position, including a recent California ruling that dismissed tribal efforts to block Kalshi’s sports contracts.

Polymarket operates outside US jurisdiction as a decentralized protocol. Its market outcomes are governed by on-chain oracles rather than a regulated clearinghouse. On the flip side, Polymarket US is building toward full CFTC compliance through the QCEX acquisition.

Insider trading

Insider trading is an open structural question for prediction markets, and the two platforms sit on opposite ends of the enforcement spectrum. On February 25, 2026, Kalshi announced both enforcement actions simultaneously, and the CFTC Enforcement Division issued a formal advisory the same day.

The first involved Kyle Langford, a longshot Republican candidate in California’s governor’s race, who bet approximately $200 on his own candidacy and then posted a screenshot of the trade on X — a case Dustin Gouker at The Event Horizon had first reported nine months earlier, noting that Langford had essentially reported himself. Kalshi’s surveillance system flagged the activity, froze his account the same day, and contacted him — Langford acknowledged the trades violated exchange rules. Kalshi imposed a $2,246.36 penalty ($246.36 in disgorgement plus a $2,000 fine) and a five-year suspension, with the fine earmarked for donation to a nonprofit providing consumer education on derivatives markets.

The second involved a MrBeast channel editor, Artem Kaptur, who traded a prediction market tied to the channel he worked for between August and September 2025, using advance knowledge of video content before it was publicly posted. Kalshi concluded the trades were based on material non-public information and imposed a $20,397.58 penalty — $5,397.58 in disgorgement plus a $15,000 fine — and a two-year suspension.

Kalshi and Polymarket US carry regulatory exposure and a formal obligation to investigate suspicious activity. Neither platform has implemented a public, systematic surveillance process comparable to what exists in traditional financial markets.

Conflict markets

Conflict markets are prediction contracts geared towards geopolitical events involving war, military action, assassination, or the fate of foreign leaders. Under CFTC Regulation 40.11, registered entities including designated contract markets like Kalshi and Polymarket US are prohibited from listing contracts that involve, relate to, or reference war, terrorism, or assassination. Offshore platforms like Polymarket operate with their own rules and have listed war and assassination contracts freely. This is why the same event can produce different outcomes on each platform, and why the media and regulators routinely conflate the two.

When US and Israeli forces killed Khamenei on February 28, 2026, both platforms had active markets on his ouster. Polymarket’s contract resolved YES and paid out $529 million in full — no CFTC death restriction applies offshore. Kalshi halted its market, settling $21.7 million in positions at the last traded price before death rather than $1, triggering widespread trader backlash. The company acknowledged its settlement language was “grammatically ambiguous” and reimbursed fees. CEO Tarek Mansour wrote on X: “We don’t list markets directly tied to death. When there are markets where potential outcomes involve death, we design the rules to prevent people from profiting from death.”

Separately, Bubblemaps flagged six Polymarket wallets — all funded within 24 hours of the strikes — that made a combined $1.2 million on the Iran strike contracts.

Senator Chris Murphy responded on X: “It’s insane this is legal. People around Trump are profiting off war and death. I’m introducing legislation ASAP to ban this.”

Senator Adam Schiff, who had led six senators in a pre-strike letter to the CFTC warning about contracts tied to death and assassination, posted after Khamenei’s death: “Gambling on war and death doesn’t just present national security risks, it also raises serious concerns about potential insider trading — presenting unscrupulous government officials with a chance to profit off the new war in Iran. These contracts are immoral. @CFTC can and must ban them.” Both were responding to activity on Polymarket, whose offshore structure is not the same as Kalshi and Polymarket US.

Mansour pushed back directly, telling Murphy in two separate posts: “The market you’re posting is unregulated and offshore” and “Regulated prediction markets are not allowed to do war markets.”

Tax reporting

Kalshi reports trading activity to the IRS and issues three tax documents: a 1099-INT for interest earned on balances, a 1099-MISC for bonuses and credits, and a 1099-B for crypto transfer proceeds — note the 1099-B covers crypto transactions only, not general event-contract trading activity. Gains and losses are calculated using FIFO accounting, and monthly P&L data is available through the platform.

Polymarket US is expected to issue 1099 forms as the platform moves out of beta, but how tax reporting will work in practice is not yet known. For traders on the global platform, tax treatment depends entirely on individual jurisdiction and the trader’s own recordkeeping. Kalshi’s tax documentation is clear, while Polymarket’s is a work in progress and requires recordkeeping if transferring from crypto assets. See our crypto tax calculator to learn more.

About The Author

Cheryle Shepstone

Cheryle is Director of Content and Strategy at DeFi Rate. She oversees the prediction market research, platform reviews, and editorial methodology behind every guide—from primary source verification through final fact-check. Before DeFi Rate, she led content and growth strategy at Catena Media, where she helped shape content and revenue strategy for regulated and financial markets. She has 20 years of experience in research and marketing strategy

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