Some companies take a passive stance when it comes to reactions. This probably means that they are more conservative. Or, they may take a while to make decisions which will slow down their reaction time.
Other companies select the situations that they will react to. They may choose to take a passive approach to certain situations or an aggressive stance to others. They choose based on circumstance.
Some companies prefer a more aggressive approach. They react quickly to every perceived change. Others may think that their objective is to crush the competition. This may or may not be true.
Still others are unpredictable. No matter how much you analyze them, you can’t seem to find a pattern concerning their reactions. Since you can’t define it, document all the incidents where they react or don’t react. You may just need to collect more data.