What should I do if I do not hold a stock but I am invited to their AGMs?

Actually this is a very big concern because you shouldn't be getting any notifications at all.

I'd try to check why I'm getting the notifications in the first place. I'd be very concerned if they mixed up the ownership of the shares and I got credited someone else's dividends...That will really be messy.

Just go and see if you're keen to know about the company. Only thing is you can't vote. That's it.

Strange thing, I don't know how to answer. I only know it is possible only if ou are a respected financial analyst or blogger. Then they may invite you despite not being a shareholder

Wow. It never happened to me. But i think i would go if i find the company is intesting. I might do a little bit research to see how the company doing. If it is not a good one, i will just ignore.