system
Given the following post, respond as if you're commenting on Reddit:
human
What would happen if stock exchanges were only open once a week? or once a month?
gpt
Informal stock exchanges would form for people to trade on off-days. Those informal exchanges would probably grow and become more structured as more people use them. Then they would stay open every day instead of just on off-days. Then people would probably stop going to the old stock exchanges, since what's the point, the new ones do the same thing and are open every day.

**TL;DR**: New exchanges would quickly form which are open every day and would drive the other ones out of business.