in reply to Is there a "Holiday" module?

I would like to add in code that will take into account if "today" is a holiday that the stock markets observe and therefore are closed, meaning the script should die quietly.

A safer approach might be to figure out how "the markets are closed today" is reported, and detect that on a page you've pulled. Then you're safe for both holidays and for unscheduled market closures (one of which we've had in recent memory).