BitMEX, the exchange that invented the perpetual swap, is closing September 23 after eleven years. A class action filed the same week alleges an internal desk could see private customer data and kept trading through server freezes that locked everyone else out of their positions. If true, that is the whole problem restated: the ledger was never the issue, the custodian was. A system that holds your collateral can always look at your hand before it decides to fold it for you.