Kalshi vs Polymarket for Investors: Full Comparison (2026)

Economic Markets: The Factor That Settles It for Macro Investors

If you are reading this comparison because you want to trade economic indicators — CPI, FOMC rate decisions, GDP, unemployment — the comparison ends here: Kalshi is the only option. Polymarket has no economic indicator markets, and no other CFTC-regulated platform offers them.

This is not a minor product gap. Kalshi's economic markets are the core reason the Federal Reserve published research about prediction markets in January 2026. The paper analyzed Kalshi's CPI and FOMC market data from 2021 to 2025 and found these markets outperformed Bloomberg consensus — the aggregated views of professional economists — in forecasting accuracy.

The mechanism is the same as in any well-functioning financial market: participants who have private information (Federal Reserve officials, bond traders, inflation-hedged corporations) aggregate that information through their trading decisions. The market price reflects this aggregated private information more accurately than surveys of economists who face no financial consequence for being wrong.

Practically, this means: two weeks before each monthly CPI release, you can open Kalshi and see not a single consensus estimate but a full probability distribution across possible outcomes. A 68% probability that CPI prints between 3.0% and 3.5%, a 22% probability it comes in below 3.0%, an 10% probability it prints above 3.5%. That distribution is more valuable for portfolio positioning than any single number.

The Fee Gap: Near Zero for Takers

Since 25 September 2026 the taker gap has all but closed. Both platforms use probability-weighted taker formulas: Polymarket US at Θ=0.0695 (max ~$1.74 per 100 contracts at 50¢) versus Kalshi at 0.07 (max $1.75). Polymarket's remaining edge is maker rebates (Θ=−0.0125, up to ~$0.31 per 100 contracts) and free withdrawals. (On Polymarket's separate international app, geopolitics markets carry no taker fee.)

However, this comparison is often irrelevant in practice. Consider who the fee difference actually matters to:

• Active traders who post resting orders — they earn Polymarket US's maker rebate.
• Investors who mostly take liquidity — at ~$1.74 on Polymarket US versus Kalshi's $1.75 per 100 contracts at 50¢, the taker gap is immaterial.
• Tax-aware investors who value a ready-made record — Kalshi provides a monthly profit-and-loss statement (Account → Tax Info), though it does not issue a 1099 for event-contract profits.

Run your own numbers. On $10,000 of monthly notional in 50/50 event contracts, Kalshi's taker fee comes to about $175 ($1.75 per 100 contracts) versus about $174 on Polymarket US (~$1.74 per 100) — roughly a $1/month gap. The difference that matters is Polymarket's maker rebate (up to ~$0.31 per 100 contracts) if you provide liquidity. Meaningful for high-volume market makers; immaterial for investors making a few trades per quarter around CPI and FOMC dates.

Regulatory Track Record: 2020 vs 2025

Both platforms now operate under CFTC oversight. But the nature and duration of that oversight differs meaningfully.

Kalshi received its CFTC Designated Contract Market (DCM) license in 2020. A DCM license is the highest regulatory standard for a US futures and event contract exchange — it requires meeting CFTC Core Principles covering financial surveillance, position limits, customer protection, and audit trail maintenance. Kalshi has operated under continuous CFTC oversight for 5 years. Outside estimates put its 2025 fee revenue at about $263.5M; Kalshi is private and has not published audited results.

Polymarket achieved US regulatory status in July 2025 through its acquisition of QCEX. Polymarket US operates as a CFTC-regulated designated contract market (DCM) — the same license class Kalshi holds — and derivatives clearing organization (DCO). It is a separate venue from Polymarket's international app, which runs on Polygon with USDC and where US residents can close existing positions but cannot open new ones.

This is not a disqualifying difference — Polymarket is legitimately CFTC-regulated. But for institutional investors who require established regulatory history in counterparty selection, Kalshi's 5-year track record is a meaningful distinction.

Custody and Counterparty Risk

Kalshi is a custodial platform. Your USD deposits are held by Kalshi (a CFTC-regulated exchange). This is the same model as a standard brokerage account — you rely on the platform's solvency and CFTC regulatory oversight to protect your funds.

Polymarket US is also custodial: your cash is held in your account at its clearinghouse, a CFTC-regulated derivatives clearing organization that holds collateral, clears trades and settles contracts. Polymarket US takes US dollars by debit card, bank transfer (ACH) or wire; withdrawals are free and go back to the original funding source.

The self-custody model — USDC held in your own Polygon wallet — belongs to Polymarket's international app, where US residents can close existing positions but cannot open new ones. For a US investor, custody no longer separates the two platforms: both hold your dollars under CFTC oversight, so the choice comes down to markets, fees and track record.

Tax Treatment: Neither Confirms a 1099 for Trades

Kalshi does not issue a 1099 for event-contract profits. It provides a monthly profit-and-loss statement (Account → Tax Info) and issues Form 1099-INT for interest and Form 1099-MISC for credits and rewards above IRS thresholds (Kalshi Help Center). The profit-and-loss statement gives you or your accountant a ready-made record of your trading results.

Polymarket US's participant agreement covers electronic delivery of tax forms including Form 1099-B, but Polymarket has not said whether one is issued for event-contract profits. Until it does, US users trading via QCEX should keep their own record of every trade. For a casual trader making ten trades a year, this is manageable. For an active trader executing hundreds of trades across 1,200+ markets, this is a significant record-keeping burden.

There is also a subtler, unsettled tax question. Some tax professionals argue that event contracts could be Section 1256 contracts; if Section 1256 applies, 60% of gains are taxed as long-term capital gains and 40% as short-term, regardless of holding period. No platform has been verified to treat or report its event contracts as Section 1256 contracts, and practitioners are split; consult a tax professional.

Market Depth and Liquidity

Polymarket wins on aggregate liquidity and event breadth. With 1,200+ active markets and a global user base including AI agents (Polystrat, deployed by Olas) trading 24/7, Polymarket's major markets — US elections, Fed rate decisions that appear on both platforms, major geopolitical events — often have tighter spreads than Kalshi's equivalents.

Kalshi wins on economic indicator liquidity specifically. Its CPI and FOMC markets are the only venue for this trading, so all participants seeking economic indicator exposure trade there. The absence of competition actually concentrates liquidity for this specific use case.

For political and global event markets where both platforms compete directly, check current spreads before trading — they vary by event and by time to resolution.

The Case for Using Both

The Kalshi vs Polymarket question is often posed as binary. In practice, for sophisticated investors, it is not.

A sensible dual-platform approach:

• Primary account: Kalshi. USD funding, economic indicator markets (CPI, FOMC, GDP), a monthly profit-and-loss statement, all 50 states (sports contracts contested in several). This is your primary venue for macro-informed trading.
• Secondary account: Polymarket. For global events where Polymarket's liquidity is superior (international elections, AI/tech events, markets unavailable on Kalshi), and for monitoring price discrepancies against Kalshi on shared markets.

Many arbitrageurs run both accounts simultaneously, trading opposite sides of shared markets when probability discrepancies appear. Fees matter significantly for this strategy — taker fees are now about equal at 50¢, so Polymarket's maker rebate on resting orders is what improves arbitrage profitability.