[dpark]

> It would be impossible to enforce a prohibition against that, as that would effectively be a requirement to sell.

So? That hardly seems impossible to enforce. You just don't allow cancellations unless they are also planned. If you're allowed to schedule recurring sells, say, 30 days in advance (I don't know what the specific rules are), you should only be able to cancel them with 30 days advance notice.

The whole point of the planned trade exemption is to allow trades to happen independent of insider knowledge. If you allow cancellations, you're allowing insider knowledge to impact the trading.