>Doing this would cause massive volatility, everybody would be stampeding in and out of assets at the same time. If you really want to stop HFT (which on the evidence available is actually nothing to do will the current market woes) you could simply make order cancellations more expensive, this would stop them all in their tracks. But I think this would solve nothing in the longer term.

I don't think he's saying they'd all be able to be sold or bought at the same time, just that 1 hour after it was bought, it could be sold.

Something bought at 8:30 could be sold at 9:30. It wouldn't make buying or selling only possible on the hour.

What then do you want Hubski to be guided by?