  As more people flock to social media to connect with others and form virtual
communities, it is important to research how members of these groups interact
to understand human behavior on the Web. In response to an increase in hate
speech, harassment and other antisocial behaviors, many social media companies
have implemented different content and user moderation policies. On Reddit, for
example, communities, i.e, subreddits, are occasionally banned for violating
these policies. We study the effect of these regulatory actions as well as when
a community experiences a significant external event like a political election
or a market crash. Overall, we find that most subreddit bans prompt a small,
but statistically significant, number of active users to leave the platform;
the effect of external events varies with the type of event. We conclude with a
discussion on the effectiveness of the bans and wider implications for the
online content moderation.
