unions

I was part of an ISP that was a customer coop. I bought a share when I signed up and then sold it when I moved away.

Another way it could be done is via dilution. Like every so often, new shares are issued to current employees based on whatever criteria they use to determine division of ownership. Existing shares remain outstanding so former employees still get dividends and voting rights, but the guy that worked there for 3 months 8 years ago isn't an equal owner to someone who joined 3 years ago and hasn't left. Though there's then the question of can people sell their shares to someone else, potentially leaving the door open for a hostile takeover when a large enough group of former employees want to cash out? If they can't sell them, what happens to the shares when an owner dies?

The first one is cleaner. Personally, I'd go with the first option but have an exception for people retiring so their shares can act as a non-transferable pension but then the shares cease to exist once they die (or exist for a limited amount of time after death for their next of kin).