There are many, many different models that can explain economic instability. It is much harder for a model to predict what would happen if you changed a rule. I

There are many, many different models that can explain economic instability. It is much harder for a model to predict what would happen if you changed a rule. In particular the uptick rule is the sort of thing that could easily have drastically different effects in a model than in real life, since it is focused on stopping "panics".