The same as with any other (private) company. You have to deal with the majority shareholders and the board/management. It's not like you have any more control

The same as with any other (private) company. You have to deal with the majority shareholders and the board/management. It's not like you have any more control if the company happens to be public anyway. Also, big companies, private or not, in most countries have to retain an accounting auditor. Also, if you are a member of the company (as in you have equity) the management has a fiduciary duty toward you. (yes, yes, sure, in practice that means very little, they can siphon off the money in many creative ways), but usually people who are already minority owners have some trust in the majority owners. In some jurisdictions there are rules about what kind of mechanisms are available for the minority shareholders, and usually the get a board seat, and so they can kind of try to audit the majority. And in the end they can still sue, or threaten to sue, or whatever. That usually doesn't help with the valuation, and since the majority has more to lose, they can usually work out some minimally satisfactory deal between themselves. Aaaaand if not, we can finally get the popcorn, because then usually it gets dirty and juicy.