In my opinion, the AIM method itself is protection against catastrophic negative price changes. As long as you have stocks for which you have full confidence will not go to zero (I only use ETF's of major indices), then catastrophic drops, whether overnight or during the day, are buying oppotunities.
Of course, if the catastrophic negative price changes are the result of the world, as we know it, coming to an end, then the value of your portfolio would probably be the least of your worries.