The turf war over who gets to police perpetual futures on individual American stocks just got a lot more interesting — because one of the two regulators in the ring has now told the court it agrees with the other one.

The Securities and Exchange Commission filed an amicus brief this week backing the Commodity Futures Trading Commission, which is being sued by an industry group that wants the CFTC’s approval of these products thrown out. The Block reported the filing on November 11, and Crypto Briefing confirmed the same day that the SEC is defending its sister agency in court.

A lawsuit about labels

The fight started on November 3, when the Capital Markets Alliance — a trade group whose members include Cboe and Citadel Securities — sued the CFTC. Its argument is essentially about labels: the group says perpetual contracts tied to single stocks are really security-based swaps, which would put them under SEC jurisdiction, not the CFTC’s. It also claims the CFTC broke the Administrative Procedure Act by failing to explain its decision, and it asked the court to vacate the approvals.

The CFTC had deemed the products approved on November 2, after a 45-day review under its Regulation 40.3 classified them as security futures products. Kalshi launched trading in the contracts on November 5, covering more than 50 US stocks and ETFs.

The court has already weighed in once, and the result was a split decision. On November 10, a federal judge denied the group’s request for a temporary restraining order — so the approvals stand for now — but signaled that, at this early stage, the challengers are likely to succeed on their argument that the CFTC overstepped its authority.

Everyone is filing a brief

The SEC’s brief pushes back directly on the lawsuit’s framing. The Capital Markets Alliance had accused the CFTC of having “gone rogue,” and the SEC’s answer, in its own words, is that this depiction — “of a CFTC gone rogue, and an SEC gone missing” — is mistaken. The agency says the CFTC’s rule changes are subject to its review and that the two regulators collaborate often, which matters when overseeing equity perpetuals.

The SEC’s move is striking because the lawsuit’s whole premise is that these products belong under SEC oversight. The SEC itself has now told the court it supports the CFTC’s approval — though, as Ledger Insights noted, the brief argues against an injunction without taking a position on the core legal question of whether the contracts are futures or swaps.

The rest of the industry has picked sides too. Coinbase, Kalshi, Kraken parent Payward, DRW Holdings, Paradigm and Jump Trading filed a joint brief defending the CFTC. On the other side, advocacy group Better Markets and former SEC Commissioner Allison Herren Lee filed briefs arguing the products are securities swaps that need the SEC’s stronger investor protections — Better Markets warned they pose “an unreasonably high risk of causing total losses to retail investors.”

The clock is ticking on a separate front: the SEC has until December 31 to decide whether to overturn the CFTC’s rule changes, and Ledger Insights reports it has given no hint which way it will go.

What it means for crypto

For the crypto world, the stakes are concrete. The platforms positioned to list these contracts include Coinbase Derivatives, Kalshi and Bitnomial — crypto-native venues that would gain a regulated on-ramp into a product Wall Street has traded offshore for years. A ruling for the challengers would push that business back overseas; a win for the CFTC keeps it on US exchanges, under a regulator the crypto industry has found friendlier.

But the legal question is far from settled. A judge has already hinted the challengers may win on the merits, and the SEC itself still holds the power to reverse the rules by year-end. The brief is a vote of confidence, not a verdict.

The Bit Take: Two regulators, one courtroom, and a product that refuses to fit neatly into either one’s box. The SEC just told a judge its sister agency isn’t rogue — but with a judge already leaning the other way and a December 31 deadline hanging over the rules, this turf war is only getting started. If you trade perps, watch the docket, not just the chart.

Sources

The Block, “SEC enters fight over who regulates perpetual derivatives on stocks in the US”, November 11, 2026 — https://www.theblock.co/news/regulation/2026-11-11-sec-enters-fight-who-regulates-perpetual-derivatives-stocks-in-us-438427
Crypto Briefing, “SEC backs CFTC in court fight over single-stock perpetual futures”, November 11, 2026 — https://cryptobriefing.com/sec-backs-cftc-perpetual-futures-lawsuit/
Ledger Insights (via The Crypto Guide), “CFTC Equity Perpetual Futures: What Changes in the US”, updated November 11, 2026 — https://thecryptoguide.org/blog/cftc-equity-perpetual-futures-us-exchanges-what-changes/