Why do so many people trade a bankrupt company's stock?
It may have some value!  Investopedia has a well-written quick article on how stock holders may still get some portion of the liquidated assets.  While there is generally little left for common shareholders if the price of those shares is tiny and some money does come back to shareholders there can still be significant profit to be made. As to why the trading volume is so high... there are many firms and hedge funds that specialize in calculating the value of and buying distressed debt and stock.  They often compete with each other to by the stock/debt that common shareholders are trying to get rid of.  In this particular case, there is a lot of popular interest, intellectual property at stake and pending lawsuits that probably boosts volume.
"In some cases, when a company purchases a minor stake, they often intend to increase the size of the stake over time. As a reference, note that Coca Cola has increased their stake in Green Mountain Coffee Roasters (GMCR) over time. It also adds some ""support"" to the price because these investors may be willing to step in and purchase the stock if there is any distress or poor performance. Finally, its generally a good ""tell"" that the stock has good things going for it and may be subject to additional interest from large investors." The stock exchange here serves as a meeting place for current shareholders who want to sell their shares to someone else. This has nothing to do with liquidation, which is a transaction between the company and its shareholders. A company does not have to be listed on an exchange to make distributions to shareholders. Good questions. I can only add that it may be valuable if the company is bought, they may buy the options. Happened to me in previous company. "Market makers, traders, and value investors would be who I'd suspect for buying the stock that is declining. Some companies stocks can come down considerably which could make some speculators buy the stock at the lower price thinking it may bounce back soon. ""Short sellers"" are out to sell borrowed stocks that if the stock is in free fall, unless the person that shorted wants to close the position, they would let it ride. Worthless stocks are a bit of a special case and quite different than the crash of 1929 where various blue chip stocks like those of the Dow Jones Industrials had severe declines. Thus, the companies going down would be like Apple, Coca-Cola and other large companies that people would be shocked to see come down so much yet there are some examples in recent history if one remembers Enron or Worldcom. Stocks getting delisted tend to cause some selling and there are some speculators may buy the stock believing that the shares may be worth something only to lose the money possibly as one could look at the bankrupt cases of airlines and car companies to study some recent cases here. Circuit breakers are worth noting as these are cases when trading may be halted because of a big swing in prices that it is believed stopping the market may cause things to settle down." ELI5 - you sell something that you don't own with the expectation that it will go down, and then you buy it back when it goes down in order to lock in profit.  You are charged fees to borrow the stock from someone else who currently owns it, and you also run the risk of the market going against you by going up. In the US, and I suspect in most of the developed world, one major point of a corporation is limited liability.  The stockholders are not on the hook for liabilities beyond their investment.  If the company does something terrible, or fails economically, it goes bankrupt.  Usually the stockholders have their investment wiped out, but they are guaranteed that they do not have to pay more in to any settlement. As Mhoran said, the risks of buying a bankrupt company are huge, and even successful bankruptcy turnarounds don't involve keeping the same stock. For instance, the GM bankruptcy was resolved by the company more or less selling all its valuable assets (brands, factories, inventory) to a new version of itself, using that money to pay off what liabilities it could, and then dissolving. The new company then issued new stock, and you had to buy the new stock to see it rise; the old stock became worthless. AA could have gone the same way; Delta could have bought it out of bankruptcy and consumed it outright, with any remaining shareholders being paid off at market value. That's probably the best the market was hoping for. Instead, the deal is a much more equal merger; AMR brings a very large airport network and aircraft fleet to the table, and Delta brings its cash, an also-considerable fleet and network, and a management team that's kept that airline solvent. The stockholders, therefore, expect to be paid off at a much higher per-share price, either in a new combined stock, in Delta stock, or in cash. "People in this case, are large institutional investors. The ""bid ask"" spread is for ""small traders"" like yourself. It is put out by the so-called specialists (or ""market makers"") and is typically good for hundreds or thousands of shares at a time. Normally, 2 points on a 50 stock is a wide spread, and the market maker will make quite a bit of money on it trading with people like yourself. It's different if a large institution, say Fidelity, wants to sell, say 1 million shares of the stock. Depending on market conditions, it may have trouble finding buyers willing to buy in those amounts anywhere near 50. To ""move"" such a large block of stock, they may have to put the equivalent of K-Mart's old ""Blue Light Special"" on, several points below." If the company went bankrupt, the issued public shares that were outstanding at the time most likely were voided, in which case your shares are most definitely gone.  The company might have done a new stock issuance coming out of bankruptcy with a different symbol, and while it could be substantially the same company, it doesn't mean much for you.  It's unfortunate this may be the case, but it is one of the risks of investing. "That's a pretty good question for a six-year-old! In addition to the good answers which point out that expectations are priced in, let's deny the premises of the question: Sales do not increase the value of a company; a company could be, for example, losing money on every sale. Share prices are (at least in theory) correlated with profits.  So let's suppose that company X is unprofitable 320 days a year and is relying upon sales in late November and December to be in the black for the year. (Hence ""black Friday"".)  Carefully examine the supposition of this scenario: we have a company that is so unprofitable that it must gamble everything on successfully convincing bargain hunting consumers in a weak economy to buy stuff they don't actually need from them and not a competitor. Why would this inspire investor confidence? There are plenty of companies that fail to meet their sales targets at Christmas, for plenty of reasons." Stock trading (as opposed to IPO) doesn't directly benefit the company. But it affects their ability to raise additional funds; if they're valued higher, they don't need to sell as many shares to raise a given amount of money.  And the stockholders are part owners of the company; their votes in annual corporate meetings and the like can add up to a substantial influence on the company's policies, so the company has an interest in keeping them (reasonably) happy. Dividends (distributing part of the company's profits to the stockholders) are one way of doing so. You're still investing in the company. The fact that you're buying someone else's share just means you're doing so indirectly, and they're dis-investing at the same time. The people who cause this sort of sell-off immediately are mostly speculators, short-term day-traders and the like. They realize that, because of the lowered potential for earnings in the future, the companies in question won't be worth as much in the future. They will sell shares at the elevated price, including sometimes shares that they borrow for the explicit purpose of selling (short selling), until the share price is more reasonable. Now, the other question is why the companies in question won't sell for as much in the future: Even if every other company in the world looks less attractive all at once (global economic catastrophe etc) people have other options. They could just put the money in the bank, or in corporate bonds, or in mortgage bonds, or Treasury bonds, or some other low-risk instrument, or something crazy like gold. If the expected return on a stock doesn't justify the price, you're unlikely to find someone paying that price. So you don't actually need to have a huge sell-off to lower the price. You just need a sell-off that's big enough that you run out of people willing to pay elevated prices. "No, the stock market is not there for speculation on corporate memorabilia.  At its base, it is there for investing in a business, the point of the investment being, of course, to make money.  A (successful) business earns money, and that makes it valuable to its owners since that money can be distributed to them.  Shares of stock are pieces of business ownership, and so are valuable.   If you knew that the business would have profit of $10,000,000 every year, and would distribute that to the owners of each of its 10,000,000 shares each year, you would know to that each share would receive $1 each year.  How much would such a share be worth to you?  If you could instead put money in a bank and get 5% a year back, to get $1 a year back you would have to put $20 into the bank.  So maybe that share of stock is worth about $20 to you.  If somebody offers to sell you such a share for $18, you might buy it; for $23, maybe you pass up the offer. But business is uncertain, and how much profit the business will make is uncertain and will vary through time.  So how much is a share of a real business worth?  This is a much harder call, and people use many different ways to come up with how much they should pay for a share.  Some people probably just think something like ""Apple is a good company making money, I'll buy a share at whatever price it is being offered at right now.""  Others look at every number available, build models of the company and the economy and the risks, all to estimate what a share might be worth, more or less.  There is no indisputable value for a share of a successful business. So, what effect does a company's earnings have on the price of its stock?  You can only say that for some of the people who might buy or sell shares, higher earnings will, all other thing being equal, have them be willing to spend more to buy it or demand more when selling it.  But how much more is not quantifiable but depends on each person's approach to the problem.  Higher earnings would tend to raise the price of the stock.  Yet there are other factors, such as people who had expected even higher earnings, whose actions would tend to lower the price, and people who are OK with the earnings now, but suspect trouble for the business is appearing on the horizon, whose actions would also tend to lower the price. This is why people say that a stock's price is determined by supply and demand." "This information is clearly ""material"" (large impact) and ""non-public"" according to the statement of the problem.  Also, decisions like United States v. Carpenter make it clear that you do not need to be a member of the company to do illegal insider trading on its stock. Importantly though, stackexchange is not a place for legal advice and this answer should not be construed as such.  Legal/compliance at Company A would be a good place to start asking questions." "It's a form of market manipulation.   It makes it look like there is high trading volume, which gets attention from speculators and technical traders who see a ton of volume and think that there is some kind of news announcement or something. People start buying it so they don't miss out on whatever it is that ""everyone else"" is doing, and the price goes up."