What happens to shareholders in the event of a buyout?

First off, I don't know why people ask these questions while leaving out details. Why would you keep the company name a secret? I could tell you more if you told me what company you were talking about. But:

When a company wants to acquire another company in the US in 2013, they pretty much always do it with the cooperation of current management of the company. They put together a tender offer to buy shares of the company which is almost always an offer to buy stock at a significant premium to current market price (at least 15% above). As soon as the tender offer is announced the stock jumps in price to some number usually below the tender offer price. This is because deals fall through because of regulatory/legal issues or because the acquirer is allowed to do due diligence after the offer and doesn't like what they find. There are people out there who are really good at handicapping that who work in risk arbitrage shops. You can't do it better than they can nor can your broker so your opinion about whether or not the deal is going to go through is irrelevant.

In the US you do not have to accept a tender offer. If enough people tender their shares so that the deal goes through, the company only has the responsibility to treat you fairly which is usually just give you rights to accept the tender price at any future date so there is little reason to not tender your shares in most cases.

Unless you have spent lots of time and effort studying risk arbitrage you can't really make a guess that is better than market price. I usually just ride these things out and see what happens. That's been right and that's been wrong but I doubt I could have done any better by lots of study.

The shareholders get bought out!

The bid could be cash or shares or cash & shares.

If the bid rumour is strong then the share price may already have risen to near, or above, the actual bid.

Furthermore there could be an announcement that the company was in bid talks but is no longer (share price may collapse). A bid could be announced. The share price may adjust to be just below the bid price if the market thinks it will go through. Or it could rise above the bid price if the market thinks the bid will be challenged and therefore increased or if the first bid attracts another bidder at a higher price.

Read all the press comment you can and try and judge which one of the above is most likely to happen (ans ask your broker for advice!!).

If it is a company that is doing very well then the best possible course of action is to wait and see what develops (do nothing).

first two question you can answer yourself

the location of the company and the law from the buyer and also for the stock that will be bought

what happens when a holder of a stock say yes and accepted an offer of amount money for each share

what happens when a holder of a stock is still a holder of an stock anoted at an stockmarket and that not took part while the take over was partial

If the predator makes a cash offer ,then you accept or decline. Accept and you get a cheque. If you decline as do many others maybe an increased offer comes. If the bidder gets a majority of acceptances the you will have to accept anyway.

The bid may come as a script offer or part cash/script offer, then as above.

If you do nothing and the take-over succeeds then you receive the accepted price for your holding.