Not only that, settlement delay can cause fraud or the appearance of fraud. In the robinhood case (if they are telling the truth), then the exchange had to fro

Not only that, settlement delay can cause fraud or the appearance of fraud. In the robinhood case (if they are telling the truth), then the exchange had to front its own cash for unsettled transfers. Furthermore, if there was instant settlement the idea of “shorts” changes: you could still borrow a stock but it is super clear who is holding it at a given moment, and how many are held by whom.