THE BLOCK: The SEC has stepped into the fight over whether exchanges can offer single-stock perpetual derivatives after a financial institution-backed Capital Markets Alliance Association sued the CFTC last week. In an amicus brief, the SEC said the CMA's depiction of "a CFTC gone rogue, and an SEC gone missing" is wrong. Others have since filed briefs, including Coinbase, Kalshi, the CME and Better Markets.