that will mean they have lost control,
They never had control over stock markets, it's opposite-market has a complete and total control of what governments do. After the crash, market forced them to take action, it's the same as selling at the bottom. Measures taken won't do anything.
Even if there are two persons left with one share holding per each, they can still push markets in any amount lower by selling those two stocks to each other. The only way to stop markets from going anywhere is to close the exchange. Bans and regulations do nothing to forces upon which markets are operating.