Company A is buying company B, what happens to the stock?
It depends on the timing of the events. Sometimes the buying company announces their intention but the other company doesn't like the deal. It can go back and forth several times, before the deal is finalized. The specifics of the deal determine what happens to the stock: The deal will specify when the cutoff is. Some people want the cash, others want the shares.  Some will speculate once the initial offer is announced where the final offer (if there is one) will end up. This can cause a spike in volume, and the price could go up or down. Regarding this particular deal I did find the following: http://www.prnewswire.com/news-releases/expedia-to-acquire-orbitz-worldwide-for-12-per-share-in-cash-300035187.html Additional Information and Where to Find It Orbitz intends to file with the SEC a proxy statement as well as other   relevant documents in connection with the proposed transaction with   Expedia. The definitive proxy statement will be sent or given to the   stockholders of Orbitz and will contain important information about   the proposed transaction and related matters. SECURITY HOLDERS ARE   URGED TO READ THE PROXY STATEMENT CAREFULLY WHEN IT BECOMES AVAILABLE   AND ANY OTHER RELEVANT DOCUMENTS FILED WITH THE SEC, AS WELL AS ANY   AMENDMENTS OR SUPPLEMENTS TO THOSE DOCUMENTS, BECAUSE THEY WILL   CONTAIN IMPORTANT INFORMATION. The proxy statement and other relevant   materials (when they become available), and any other documents filed   by Expedia or Orbitz with the SEC, may be obtained free of charge at   the SEC's website, at www.sec.gov. In addition, security holders will   be able to obtain free copies of the proxy statement from Orbitz by   contacting Investor Relations by mail at ATTN: Corporate Secretary,   Orbitz Worldwide, Inc., 500 W. Madison Street, Suite 1000, Chicago,   Illinois 60661. I think the correct statement is that Expedia wants to buy Orbitz for $12/share. The market price is $11, which means there is somebody willing to sell for that price. But you can't say that a stock price of $11 means that everybody is willing to sell for that price. And Expedia is unlikely to bid $12/share for just 40% of Orbitz shares; they'll want at least a controlling majority.
First, the stock does represent a share of ownership and if you have a different interpretation I'd like to see proof of that. Secondly, when the IPO or secondary offering happened that put those shares into the market int he first place, the company did receive proceeds from selling those shares. While others may profit afterward, it is worth noting that more than a few companies will have secondary offerings, convertible debt, incentive stock options and restricted stock that may be used down the road that are all dependent upon the current trading share price in terms of how useful these can be used to fund operations, pay executives and so forth. Third, if someone buys up enough shares of the company then they gain control of the company which while you aren't mentioning this case, it is something to note as some individuals buy stock so that they can take over the company which happens. Usually this has more of an overall plan but the idea here is that getting that 50%+1 control of the company's voting shares are an important piece to things here. The stock market is just like any other market, but stocks are bought and sold here. Just like you buy and sell your electronics at the electronics market, this is a place where buyers and sellers come together to buy and sell shares or stocks or equity, no matter what you call it. What are these shares?  A share is nothing but a portion of ownership of a company. Suppose a company has 100 shares issued to it, and you were sold 10 out of those, it literally means you are a 10% owner of the company. Why do companies sell shares? Companies sell shares to grow or expand. Suppose a business is manufacturing or producing and selling goods or services that are high in demand, the owners would want to take advantage of it and increase the production of his goods or services. And in order to increase production he would need money to buy land or equipment or labor, etc. Now either he could go get a loan by pledging something, or he could partner with someone who could give him money in exchange for some portion of the ownership of the company. This way, the owner gets the money to expand his business and make more profit, and the lender gets a portion of profit every time the company makes some. Now if the owner decides to sell shares rather than getting a loan, that's when the stock market comes into the picture. Why would a person want to trade stocks? First of all, please remember that stocks were never meant to be traded. You always invest in stocks. What's the difference? Trading is short term and investing is long term, in very simple language. It's the greed of humans which led to this concept of trading stocks. A person should only buy stocks if he believes in the business the company is doing and sees the potential of growth. Back to the question: a person would want to buy stocks of the company because: How does a stock market help society? Look around you for the answer to this question. Let me give you a start and I wish everyone reading this post to add at least one point to the answer. Corporations in general allow many people come together and invest in a business without fear that their investment will cause them undue liability - because shareholders are ultimately not liable for the actions of a corporation. The cornerstone North American case of how corporations add value is by allowing many investors to have put money towards the railroads that were built across America and Canada. For The stock market in particular, by making it easier to trade shares of a company once the company sells them, the number of people able to conveniently invest grows exponentially. This means that someone can buy shares in a company without needing to knock door to door in 5 years trying to find someone to sell to. Participating in the stock market creates 'liquidity', which is essentially the ease with which stocks are converted into cash. High liquidity reduces risk overall, and it means that those who want risk [because high risk often creates high reward] can buy shares, and those who want low risk [because say they are retiring and don't have a risk appetite anymore] can sell shares. "Learn something new every day... I found this interesting and thought I'd throw my 2c in. Good description (I hope) from Short Selling: What is Short Selling First, let's describe what short selling means when you purchase shares of stock. In purchasing stocks, you buy a piece of ownership in the company. You buy/sell stock to gain/sell ownership of a company. When an investor goes long on an investment, it means that he or she has bought a stock believing its price will rise in the future. Conversely, when an investor goes short, he or she is anticipating a decrease in share price. Short selling is the selling of a stock that the seller doesn't own. More specifically, a short sale is the sale of a security that isn't owned by the seller, but that is promised to be delivered.  Still with us? Here's the skinny: when you short sell a stock, your broker will lend it to you. The stock will come from the brokerage's own inventory, from another one of the firm's customers, or from another brokerage firm. The shares are sold and the proceeds are credited to your account. Sooner or later, you must ""close"" the short by buying back the same number of shares (called covering) and returning them to your broker. If the price drops, you can buy back the stock at the lower price and make a profit on the difference. If the price of the stock rises, you have to buy it back at the higher price, and you lose money. So what happened? The Plan The Reality Lesson I never understood what ""Shorting a stock"" meant until today. Seems a bit risky for my blood, but I would assume this is an extreme example of what can go wrong. This guy literally chose the wrong time to short a stock that was, in all visible aspects, on the decline.  How often does a Large Company or Individual buy stock on the decline... and send that stock soaring? How often does a stock go up 100% in 24 hours? 600%?  Another example is recently when Oprah bought 10% of Weight Watchers and caused the stock to soar %105 in 24 hours. You would have rued the day you shorted that stock - on that particular day - if you believed enough to ""gamble"" on it going down in price." "But speculation is absolutely intended to happen, and is considered necessary for healthy a investment environment.  What I am saying, however, is that this desire to rid the world of HFT appears to be moral rather than logical. There is very little reason to eliminate HFT as it stands, although there appears to be a propensity for very emotional responses to the basic concept. Ones I can appreciate. However I am suggesting they are misguided as the people who should be upset with HFT are the hedge fund managers and day traders they are outwitting, not you or me who buy and sell shares on a whim every so often. If you want to ban day traders that is a separate argument I don't want to go into.  The idea that these computer algorithms are all set to ""sell,sell,sell"" is provably nonsensical. If that were the case, all of the HFT participants would have gone massively bankrupt during the flash crashes. Also, it is quite patently the case that somebody has to be buying in order for anybody to sell. Saying ""this is what caused some of the crashes"" is just your desire for a simple explanation. It must have been more complex than this, and to my knowledge none of these crashes have been adequately explained although some poorly designed algorithms have been implicated. Note that in one of these cases IIRC a fund closed its doors due to the losses, and the market was largely unaffected. So it seems like a problem that self corrects in this case, and one that only *harms* the participant that erred.  Also, to correct a basic misunderstanding, selling happens all of the time, and does not inherently drive the price down. There are by definition an *equal number of sales to purchases*. What drives the price down is *the people buying being willing to pay less*.  EDIT: as another aside, a point I have made elsewhere and seems suitable to make here: flash crashes, whilst causing panic, are again something only the professional intra-day trading community are likely to be affected by. Their very name implies so. The reason being that anybody investing based on the *long term investment potential* of a company will only benefit in the temporary drop in price, as they can purchase more of the company at a bargain price. Any intelligent investor will not be fazed by the drop in price, as price has *no bearing on a company's real value*, and stocks do tend towards this value over time, whatever happens over the short term. The only case in which it could is if the company owns a large portfolio of stock that itself devalues dramatically that they intended to sell and as a result experience cash flow problems. This is so incredibly unlikely with a flash crash as to be ignored." Absolutely. In fact, all stock purchases of more than 5% of a company's stock must be reported to the SEC, so assuming A and B are publicly traded companies in the US, the purchase would likely be a matter of public record.  There are probably special cases where this could cause problems, however; any case where A's purchase of B's stock (or vice versa) runs afoul of regulation would be one such case. For example, if company A wants to own a controlling interest in company B and appoint members of its board of directors and both companies were in the same heavily-concentrated market, regulators may frown on the potential for decreased competition. Such regulations may apply to any purchase of a controlling interest in a company, though. You can look at the company separately from the ownership. The company needs money that it doesn't have, therefore it needs to borrow money from somewhere or go bankrupt.  And if they can't get money from their bank, then they can of course ask people related to the company, like the two shareholders, for a loan. It's a loan, like every other loan, that needs to be repaid. How big the loan is doesn't depend on the ownership, but on how much money each one is willing and capable of giving. The loan doesn't give them any rights in the company, except the right to get their money back with interest in the future.  Alternatively, such a company might have 200 shares, and might have given 75 to one owner and 25 to the other owner, keeping 100 shares back. In that case, the shareholders can decide to sell some of these 100 shares. I might buy 10 shares for $1,000 each, so the company has now $10,000 cash, and I have some ownership of the company (about 9.09%, and the 75% and 25% shares have gone down, because now they own 75 out of 110 or 25 out of 110 shares). I won't get the $10,000 back, ever; it's not a loan but the purchase of part of the company. It basically only affects the company's dealings with its own stock, not with operational concerns.  If the company were to offer more stock for sale, it would get less cash.  If it had a stock buy-back program, it could buy more shares for the same money.  If it was to offer to acquire another company in exchange for its own stock, the terms would be less attractive to the other company's owners.  Employee stock remuneration, stock options, and so forth would be affected, so there might be considerations and tax consequences for the company. It doesn't matter which exchange a share was purchased through (or if it was even purchased on an exchange at all--physical share certificates can be bought and sold outside of any exchange). A share is a share, and any share available for purchase in New York is available to be purchased in London. Buying all of a company's stock is not something that can generally be done through the stock market. The practical way to accomplish buying a company out is to purchase a controlling interest, or enough shares to have enough votes to bind the board to a specific course of action. Then vote to sell all outstanding shares to another company at a particular fixed price per share. Market capitalization is an inaccurate measure of the size of a company in the first place, but if you want to quantify it, you can take the number of outstanding shares (anywhere and everywhere) and multiply them by the price on any of the exchanges that sell it. That will give you the market capitalization in the currency that is used by whatever exchange you chose.