Ask which came first and the honest answer flatters Kalshi: it has held a CFTC contract market designation since November 2020, before Polymarket had any legal way to sign up a US customer. Ask which one has more total volume on its books today and the answer flips toward Polymarket's international platform, which built the biggest prediction-market liquidity pool anywhere by simply not being available to Americans.
One exchange, or two exchanges wearing one name?
This is the part people get backwards. Kalshi is a single company — Yes/No contracts, CFTC-regulated, one rulebook. Polymarket is a brand attached to two separate businesses: polymarket.com, the original crypto-funded platform that a 2022 CFTC settlement removed from the US market, and Polymarket US (legally QCX LLC), a different exchange Polymarket acquired and relaunched for US customers in December 2025, waitlist gone by May 2026. A Kalshi account is a Kalshi account everywhere. A "Polymarket account" depends entirely on which of the two sites issued it.
Kalshi vs Polymarket, side by side
| Kalshi | Polymarket | |
|---|---|---|
| US regulator | CFTC, DCM since November 2020 | CFTC oversees Polymarket US (QCX) only; international site has no US authorization |
| US access | Yes, was built US-first | Only via Polymarket US (QCX), relaunched Dec 2025; polymarket.com still geo-blocks US IPs |
| Funding | Bank / ACH / wire, USD | USDC on Polygon (international); bank/KYC rails (Polymarket US) |
| Regulatory history | Clean federal designation, then a 2026 state-law fight over sports contracts | $1.4M CFTC settlement (2022) for the international platform, then a fresh US entity built to avoid repeating it |
| Company origin | Founded 2018 by Tarek Mansour and Luana Lopes Lara, New York | Founded 2020; US rail is a separately acquired exchange (QCX), not the original crypto platform |
| Sports contracts | Contested state by state — blocked in Michigan (Jun 2026), enjoined for Tennessee (Feb 2026), backed by the Third Circuit in NJ (Apr 2026) | Same category of legal exposure on the US rail, arriving later and with less court history so far |
Is Polymarket legit if it already paid a CFTC fine?
Paying the fine is arguably the legitimizing move, not the disqualifying one — the international platform settled with the CFTC in 2022 rather than keep operating unregistered, and Polymarket's response was to go build (or buy) an actual regulated US entity instead of quietly ignoring the market. That doesn't erase the history. It does mean the fair comparison isn't "Kalshi is legitimate, Polymarket is not" — it's that Kalshi never needed the do-over and Polymarket did.
Where the state fight leaves both of them
Neither company gets to claim "legal sports betting nationwide," and neither should. Kalshi has the longer public court record: New Jersey, Michigan, Tennessee, and a July 2026 letter from 44 state attorneys general to the CFTC questioning its authority over sports contracts at all. Polymarket US inherited the same unresolved question the moment it relaunched in December 2025 — it just hasn't accumulated as many rulings yet, which is a difference in timing, not in legal footing.
Neither product is presented here as a way to make money. Kalshi and Polymarket contracts both settle at $1 or $0 — you can lose the full premium on either. If tracking these positions stops feeling like research and starts feeling like chasing losses, that's the signal to stop, not to switch platforms.
Which one for who
A US trader who wants the simplest possible regulatory story picks Kalshi — one company, one CFTC record, no "wait, which site do you mean" conversation. A trader outside the US who wants the deepest liquidity and is fine settling in USDC picks polymarket.com. A US trader who specifically wants Polymarket's markets and brand has to go out of their way to land on Polymarket US (QCX) rather than the international site most headlines are actually about — and should know that's a newer, less battle-tested rail than either Kalshi or Polymarket's original platform.