Why don't forced buy-ins of short sold stock happen much more frequently?
Nobody is going to short sell stocks through a lender that forces people to buy in as soon as it is getting good for them. For the lenders to sell their positions they need buyers on the other side. For a large brokerage that means they should always be able to find another lender. For many contracts the client may have no idea they are a lender as lending is part of their agreement with the broker "Many investors don't invest for the short term and so a stock ""nose-diving"" in the short run will not affect their long term strategy so they will simply hold on to it until it recovers. Additionally funds that track an index have to hold on to the constituents of that index no matter what happens to its value over the period (within trading limits). Both of these kinds of investors will be able to lend stock in a company out and not trigger a forced buy-in on a short term change. If the underlying long-term health of the company changes or it is removed from indices it is likely that this will change, however. Employee stock plans and other investors who are linked directly to the company or who have a vested interest in the company other than in a financial way will also be unwilling (or unable) to sell on a down turn in the company. They will similarly be able to lend their stock in the short term."
Short sellers have to pay interest on the borrowings to the shareholders. Although many times brokers don't pass on these earnings to the shareholders, this is the exchange. hmmm. I think it's because in both cases, you must pay for it up front, before the positions are closed out. You own nothing except the right to buy the stock re: the call, and the obligation to buy the stock re: the short.  You buy a call, but must borrow the stock, for which you must put some margin collateral and there is a cost to borrow. You pay for that, of course.  I wouldn't call it lending though. They have been changing over Immelts tenor. Didn't know he was stepping down though.       Share buybacks can be for a variety of reasons. They feel stock price is undervalued, they want to support their current shareholders, debt is cheap so they can change their wacc, they prefer to return capital in a way that does not increase expected dividends in the future (something about dividends being sticky, and the a cut in dividends Make it look like company is doing bad), etc. "The simple answer could be that one or more ""people"" decided to buy. By ""people,"" I don't mean individual buyers of 100 shares like you or me, but typically large institutional investors like Fidelity, who might buy millions of shares at a time. Or if you're talking about a human person, perhaps someone like Warren Buffett. In a ""thinly"" traded small cap stock that typically trades a few hundred shares in a day, an order for ""thousands"" could significantly move the price. This is one situation where more or less ""average"" people could move a single stock." SeekingAlpha has an article about short squeezes that states: The higher the number of days to cover means the possibility for a short squeeze is greater, and the potential size of the short squeeze is also greater Logically, this makes sense. A short squeeze occurs when a lack of supply meets excess demand for a stock, so the potential for a squeeze increases when supply and demand begin to get out of equilibrium. Think of two things that would cause the days to cover to increase and what effect they would have on supply and demand.  The current short interest (numerator) increases. This implies that if some event triggers short sellers to cover their position, there are a higher number of short sellers who will need to do so. This heightens the chances that demand will exceed supply.  The average daily volume (denominator) decreases. This implies that fewer investors are trading the stock, so if an event triggers short sellers to cover their positions, there might not be enough traders in the market willing to sell their shares. (Obviously, if a short-squeeze occurs, volume may increase because traders who were unwilling to sell their shares become willing). This is a gross simplification as there are a few different ways to do this. The principle overall is the same though. To short a stock, you borrow X shares from a third party and sell them at the current price. You now owe the lender X shares but have the proceeds from the sale. If the share price falls you can buy back those shares at the new lower price, return them to the lender and pocket the difference. The risk comes when the share price goes the other way, you now owe the lender the new value of the shares, so have to find some way to cover the difference. This happened a while back when Porsche made a fortune buying shares in Volkswagen from short sellers, and the price unexpectedly rose. "You can't short a stock unless there is someone willing and able to ""lend"" shares to you. And there are several reasons why that might not be the case. First, BSFT is a ""new"" stock, which means that NO ONE has held it very long. It's much easier to short IBM or Exxon Mobil, where there are some long-term holders who would like to earn a little extra money lending you THEIR shares. But if ""everyone"" involved is busy buying or selling the stock, there won't be many people to lend it. That's not manipulation, that's just the market. Another reason may be a large ""short"" interest. That is many OTHERS have shorted it before you. That's dangerous for you, because if some lenders want to pull their shares off the market, they can cause a ""short squeeze"" that will drive the price much higher.  And stock shortages can be orchestrated by the company or large investors to artificially drive the price higher. Unless you have a lot of experience, don't try shorting small cap stocks. Try to gain some experience with large caps like IBM or Exxon Mobil first. Those are stocks that people at least can't ""play games"" with. YOu will win or lose based on the market itself." "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." "For any large company, there's a lot of activity, and if you sell at ""market"" your buy or sell will execute in seconds within a penny or two of the real-time ""market"" price.  I often sell at ""limit"" a few cents above market, and those sell within 20 minutes usually.  For much smaller companies, obviously you are beholden to a buyer also wanting that stock, but those are not on major exchanges.  You never see whose buy order you're selling into, that all happens behind the curtain so to speak." You can't predict when to buy a stock during the day to guarantee not having a loss for the day. In the short run stock prices are really pretty random. There are many day traders who try to accomplish exactly this and most of them lose money. If you don't believe me, create an account on Investopedia and use their free stock market simulator and try day trading for a few months. There are rules that prevent two of the reactive measures you suggest from occurring. First, on the date of and shortly following an IPO, there is no stock available to borrow for shorting. Second, there are no put options available for purchase. At least, none that are listed, of the sort you probably have in mind. In fact, within a day or two of the LinkedIn IPO, most (all?) of the active equity traders I know were bemoaning the fact that they couldn't yet do exactly what you described i.e. buying puts, or finding shares to sell short. There was a great deal of conviction that LinkedIn shares were overpriced, but scant means available to translate that market assessment into an influence of market value. This does not mean that the Efficient Markets Hypothesis is deficient. Equilibrium is reached quickly enough, once the market is able to clear as usual. The original owner of the shares can pledge their shares to be short, and they earn interest from lending their shares. The conditions of this arrangement are detailed in standard agreements all market participants sign with their broker, or clearinghouse, or with the exchange, or with the self regulatory agency. Stocks within the same class are identical, despite someone's sentiment to an old share certificate that their grandparents gave them, and as such can be sold and returned to the beneficial owner multiple times with no difference. That is how it is supposed to work anyway, as naked shorting involves selling fictional shares that have no beneficial owner. So there are market inefficiencies in this practice, but the agreements between market participants are sound and answers your question about how. shorting mbs required buying a cds. part of the reason demand for mbs was so strong was because the cds was so cheap, and it seemed like risk free profit.  more people buying cds would have decreased mbs demand.  mbs are a FI security, so lower demand=higher interest rates "Note: the answer below is speculative and not based on any first-hand knowledge of pump-and-dump schemes. The explanation with spamming doesn't really makes sense for me. Often you see a stock jump 30% or more in a single day at a particular moment in time. Unlikely that random people read their emails at that time and decide to buy. What I think happens is the pumper does a somewhat risky thing: starts buying a lot of shares of a stock that has declined a lot and had low volumes during the previous days. As the price starts to increase other people start to notice the jump and join the buying spree (also don't forget that some probably use buy-stop orders which are triggered when the price reaches a particular level). Also there should be some automatic trading involved (maybe HFT firms do pump-and-dumps) as you have to trade a big volume in a relatively short time span. I think it is unlikely to be done by human operators. Another explanation would be that there is a group of pumpers (to spread the risk so to speak). Update: As I think more of it, it is not necessary to buy ""a lot of shares"". You could buy some shares, sell them to another pumper and buy from them again at a higher price in several iterations. I think this could also work if you do it fast enough. These scheme makes sense only you previously bought many shares at the low price, possibly during several weeks. Once the price is pumped high enough you can start selling the shares you previously bought (in the days preceding the pump)." "There are people (well, companies) who make money doing roughly what you describe, but not exactly. They're called ""market makers"". Their value for X% is somewhere on the scale of 1% (that is to say: a scale at which almost everything is ""volatile""), but they use leverage, shorting and hedging to complicate things to the point where it's nothing like a simple as making a 1% profit every time they trade. Their actions tend to reduce volatility and increase liquidity. The reason you can't do this is that you don't have enough capital to do what market makers do, and you don't receive any advantages that the exchange might offer to official market makers in return for them contracting to always make both buy bids and sell offers (at different prices, hence the ""bid-offer spread""). They have to be able to cover large short-term losses on individual stocks, but when the stock doesn't move too much they do make profits from the spread. The reason you can't just buy a lot of volatile stocks ""assuming I don't make too many poor choices"", is that the reason the stocks are volatile is that nobody knows which ones are the good choices and which ones are the poor choices. So if you buy volatile stocks then you will buy a bunch of losers, so what's your strategy for ensuring there aren't ""too many""? Supposing that you're going to hold 10 stocks, with 10% of your money in each, what do you do the first time all 10 of them fall the day after you bought them? Or maybe not all 10, but suppose 75% of your holdings give no impression that they're going to hit your target any time soon. Do you just sit tight and stop trading until one of them hits your X% target (in which case you start to look a little bit more like a long-term investor after all), or are you tempted to change your strategy as the months and years roll by? If you will eventually sell things at a loss to make cash available for new trades, then you cannot assess your strategy ""as if"" you always make an X% gain, since that isn't true. If you don't ever sell at a loss, then you'll inevitably sometimes have no cash to trade with through picking losers. The big practical question then is when that state of affairs persists, for how long, and whether it's in force when you want to spend the money on something other than investing. So sure, if you used a short-term time machine to know in advance which volatile stocks are the good ones today, then it would be more profitable to day-trade those than it would be to invest for the long term. Investing on the assumption that you'll only pick short-term winners is basically the same as assuming you have that time machine ;-) There are various strategies for analysing the market and trying to find ways to more modestly do what market makers do, which is to take profit from the inherent volatility of the market. The simple strategy you describe isn't complete and cannot be assessed since you don't say how to decide what to buy, but the selling strategy ""sell as soon as I've made X% but not otherwise"" can certainly be improved. If you're keen you can test a give strategy for yourself using historical share price data (or current share price data: run an imaginary account and see how you're doing in 12 months). When using historical data you have to be realistic about how you'd choose what stocks to buy each day, or else you're just cheating at solitaire. When using current data you have to beware that there might not be a major market slump in the next 12 months, in which case you won't know how your strategy performs under conditions that it inevitably will meet eventually if you run it for real. You also have to be sure in either case to factor in the transaction costs you'd be paying, and the fact that you're buying at the offer price and selling at the bid price, you can't trade at the headline mid-market price. Finally, you have to consider that to do pure technical analysis as an individual, you are in effect competing against a bank that's camped on top of the exchange to get fastest possible access to trade, it has a supercomputer and a team of whizz-kids, and it's trying to find and extract the same opportunities you are. This is not to say the plucky underdog can't do well, but there are systematic reasons not to just assume you will. So folks investing for their retirement generally prefer a low-risk strategy that plays the averages and settles for taking long-term trends."