Why does selling and then rebuying stock not lead to free money?
You are misunderstanding what makes the price of a stock go up and down. Every time you sell a share of a stock, there is someone else that buys the stock.  So it is not accurate to say that stock prices go down when large amounts of the stock are sold, and up when large amounts of the stock are bought.  Every day, the amount of shares of a stock that are bought and sold are equal to each other, because in order to sell a share of stock, someone has to buy it. Let me try to explain what actually happens to the price of a stock when you want to sell it. Let's say that a particular stock is listed on the ticker at $100 a share currently.  All this means is that the last transaction that took place was for $100; someone sold their share to a buyer for $100. Now let's say that you have a share of the stock you'd like to sell.  You are hoping to get $100 for your share.  There are 2 other people that also have a share that they want to sell.  However, there is only 1 person that wants to buy a share of stock, and he only wants to pay $99 for a share.  If none of you wants to sell lower than $100, then no shares get sold.  But if one of you agrees to sell at $99, then the sale takes place.  The ticker value of the stock is now $99 instead of $100. Now let's say that there are 3 new people that have decided they want to buy a share of the stock.  They'd like to buy at $99, but you and the other person left with a share want to sell at $100.  Either one of the sellers will come down to $99 or one of the buyers will go up to $100.  This process will continue until everyone that wants to sell a share has sold, and everyone who wants to buy a share has bought.  In general, though, when there are more people that want to sell than buy, the price goes down, and when there are more people that want to buy than sell, the price goes up. To answer your question, if your selling of the stock had caused the price to go down, it means that you would have gotten less money for your stock than if it had not gone down.  Likewise, if your buying the stock had caused it to go up, it just means that it would have cost you more to buy the stock.  It is just as likely that you would lose money doing this, rather than gain money. "There are several reasons. First, if you sell your stock ""at any price"", you may be selling it for less than you originally bought it for.  Thus you will take a loss right at the beginning of your scheme.  If you ""rinse and repeat"", the problem only gets worse.  Every time you sell your stock, you will have to sell it at an even lower price in order to lower the price even more.  Then you buy it back and. . . just resell it an even lower price?  It should be clear that you are not making any money this way. Second, even if you don't sell it at an absolute loss, you must sell it at a relative loss in order to lower the price.  In other words, if someone will currently buy your shares for $X, and you want to lower the price, you must sell them for less than $X.  But you could have made more money by selling them for $X, since someone was already willing to buy them at that price.  In order to bring the price down significantly, you have to sell the stock for less than people currently believe it is worth, which means you're incurring a loss relative to just selling it at the market rate.  Of course, you can still make money if it goes back up again, but selling it at an extra loss this way just makes it harder to break even. Third, if you sell the stock at $X, whoever you sold it to is not going to sell it right back to you at $X, because then they would not make any money.  You could in theory buy it from someone else, but the same principle holds: if the stock price has just gone down, people who have it may be waiting for it to go back up.  This is doubly true if anyone suspects you have been trying to manipulate the stock price, because they will then suspect that the price drop is artificial and it will soon go back up. Fourth, even if someone did sell it right back to you at the price you sold it for, then what?  You now hold the stock at a lower price, but you don't gain unless it goes back up.  If it wasn't going up before until you took action, there is no reason to suppose it will go back up now.  In fact, if you had enough shares to significantly influence the price, other people may have been fooled into thinking the value is actually lower now. The basic problem is that, in order for you to buy it at a low price, someone else has to sell it at that low price.  It is easy to sell someone a stock for less than it's worth, but it will be hard to get people to sell it back to you for less than it's worth.  If you engage in deceptive practices to get people to do this, you may be guilty of securities fraud." "There are a few people that do this for a living. They are called ""market makers"" or ""specialists"" in a particular stock. First of all, this requires a lot of capital. You can get burned on a few trades, a process known as ""gambler's ruin,"" but if you have enough capital to weather the storm, you can make money. Second, you have to be ""licensed"" by the stock market authorities, because you need to have stock market trading experience and other credentials. Third, you are not allowed to buy and sell at will. In order to do your job, you have to ""balance the boat,"" that is buy, when others are selling, and sell, when others are buying, in order to keep the market moving in two directions. It's a tough job that requires a lot of experience, plus a license, but a few people can make a living doing this." I think the simple answer to your question is: Yes, when you sell, that drives down the price. But it's not like you sell, and THEN the price goes down. The price goes down when you sell. You get the lower price.  Others have discussed the mechanics of this, but I think the relevant point for your question is that when you offer shares for sale, buyers now have more choices of where to buy from. If without you, there were 10 people willing to sell for $100 and 10 people willing to buy for $100, then there will be 10 sales at $100. But if you now offer to sell, there are 11 people selling for $100 and 10 people buying for $100. The buyers have a choice, and for a seller to get them to pick him, he has to drop his price a little. In real life, the market is stable when one of those sellers drops his price enough that an 11th buyer decides that he now wants to buy at the lower price, or until one of the other 10 buyers decides that the price has gone too low and he's no longer interested in selling. If the next day you bought the stock back, you are now returning the market to where it was before you sold. Assuming that everything else in the market was unchanged, you would have to pay the same price to buy the stock back that you got when you sold it. Your net profit would be zero. Actually you'd have a loss because you'd have to pay the broker's commission on both transactions. Of course in real life the chances that everything else in the market is unchanged are very small. So if you're a typical small-fry kind of person like me, someone who might be buying and selling a few hundred or a few thousand dollars worth of a company that is worth hundreds of millions, other factors in the market will totally swamp the effect of your little transaction. So when you went to buy back the next day, you might find that the price had gone down, you can buy your shares back for less than you sold them, and pocket the difference. Or the price might have gone up and you take a loss. The main thing you're missing is that while you bear all the costs of manipulating the market, you have no special ability to capture the profits yourself. You make money by buying low and selling high. But if you want to push the price up, you have to keep buying even though the price is getting high. So you are buying high. This gives everyone, including you, the opportunity to sell high and make money. But you will have no special ability to capture that -- others will see the price going up and will start selling within a tiny fraction of a second. You will have to keep buying all the shares they keep selling at the artificially inflated price. So as you keep trying to buy more and more to push the price up enough to make money, everyone else is selling their shares to you. You have to buy more and more shares at an inflated price as everyone else is selling while you are still buying. When you switch to selling, the price will drop instantly, since there's nobody to buy from you at the inflated price. The opportunity you created has already been taken -- by the very people you were trading with. Billions have been lost by people who thought this strategy would work.
There are multiple factors at play that drive stock price movements, but one that can be visualized is that stocks can be priced relative to other (similar stocks).  When one stock price goes up without fundamental changes (i.e. daily market noise/movements), it becomes slightly more expensive relative to it's peers.  Opportunists will sell the now slightly more expensive stock, while others may buying the slightly cheaper (relatively) peer stock.    Imagine millions of transactions like this happening throughout each hour, downward selling pressure on a stock that rises too fast in value relative to it's peers or the market, and upward buying pressure on stocks that are relatively cheaper than it's peers.  It pushes two stocks towards an equilibrium that is directionally the same.    Another way to think of it is lets say tomorrow there is $10B in net new dollars moved into buy orders for stocks that comes from net selling of bonds (this is also partly why bonds/stocks are generally inversely related).  That money goes to buys stocks ABC, XYZ, EFG.  As the price of those goes up with more buying pressure, stocks JKL, MNO, PQR are relatively a tad cheaper, so some money starts to flow into there.  Repeat until you get a large majority of the stocks that buyers are willing to buy and you can see why stocks move in the same direction a lot of times. "Other than the inconvienent fact that Treasury cannot sell to the Fed by law your theory is nice. You forget the step where the open market buys from the Treasury since they desire bonds to invest in, and the Fed can buy only from the open market.  Secondly, the Fed does not give cash to the Treasury. The mint (a branch of the Treasury, not the Fed) prints cash.  So it seems your understanding of how the money system works is quite wrong, yet since this is the Economy subreddit instead of the Economics subreddit, I expect you to get upvotes for saying what is popular even though it is laughably incorrect.  You seem to not like cash that was not ""even existing previously"". All cash was not existing previously. How do you expect people to make transactions? Barter?  You call them interest free loans (but above claimed they will never be paid back?), but then the Fed is making a profit on them? It seems you contradict yourself with all that handwaving.  It would be interesting for you to explain how (and why) money (not cash) gets added and removed to the economy.   Yay for ignorance!" Why do companies exist? Well, the corporate charter describes why the company exists. Usually the purpose is to enrich the shareholders. The owners of a company want to make money, in other words. There are a number of ways that a shareholder can make money off a stock: As such, maintaining the stock price and dividend payouts are generally the number one concern for any company in the long term. Most of the company's business is going to be directed towards making the company more valuable for a future buyout, or more valuable in terms of what it can pay its shareholders directly. Note that the company doesn't always need to be worried about the specifics of the day-to-day moves of the stock. If it keeps the finances in line - solid profits, margins, earnings growth and the like - and can credibly tell people that it's generally a valuable business, it can usually shrug off any medium-term blips as market craziness. Some companies are more explicitly long-term about things than others (e.g. Berkshire Hathaway basically tells people that it doesn't care all that much about what happens in the short term).  Of course, companies are abstractions, and they're run by people. To make the people running the company worry about the stock price, you give them stock. Or stock options, or something like that. A major executive at a big company is likely to have a significant amount of stock. If the company does well, he does well; if it does poorly, he does poorly. Despite a few limitations, this is really a powerful incentive. If a company is losing a lot of money, or if its profits are falling so it's just losing a lot of its value as a business, the owners (stockholders) tend to get upset, and may vote in new management, or launch some sort of shareholder lawsuit. And, as previously noted, to raise funds, a company can also issue new shares to the market as a secondary offering as well (and they can issue fewer shares if the price is high - meaning that whatever the company is worth afterward, the existing owners own proportionally more of it). &gt; The only problem I see with stock options is that they expire  You're on to something: the reason why some prefer to write (sell) options instead of buying. Neutral to bullish on crude oil? Sell puts on /CL at 90-95% probability OTM. You keep your money if the underlying moves up or does nothing, within the days to expiration. The ultimate reason to own stock is to receive cash or cash equivalents from the underlying security. You can argue that you make money when stock is valued higher by the market, but the valuation should (though clearly not necessarily is) be based on the expected payout of the underlying security. There are only three ways money can be returned to the shareholder: As you can see, if you don't ask for dividends, you are basically asking for one of the top two too occur - which happens in the future at the end of the company's life as an independent entity. If you think about the time value of money, money in the hand now as dividends can be worth more than the ultimate appreciation of liquidation or acquisition value. Add in uncertainty as a factor for ultimate value, and my feeling is that dividends are underpaid in today's markets. This answer will assume you know more math than most. An ideal case: For the point of argument, first consider the following admittedly incorrect assumptions: 1)  The prices of all assets in your investment universe are continuously differentiable functions of time. 2)  Investor R (for rebalance) continuously buys and sells in order to maintain a constant proportion of each of several investments in his portfolio. 3)  Investor P (for passive) starts with the same portfolio as R, but neither buys nor sells Then under the assumptions of no taxes or trading costs, it is a mathematical theorem that investor P's portfolio return fraction will be the weighted arithmetic mean of the return fractions of all the individual investments, whereas investor R will obtain the weighted geometric mean of the return fractions of the individual investments. It's also a theorem that the weighted arithmetic mean is ALWAYS greater than or equal to the weighted geometric mean, so regardless of what happens in the market (given the above assumptions) the passive investor P does at least as well as the rebalancing investor R.  P will do even better if taxes and trading costs are factored in. The real world:  Of course prices aren't continuously differentiable or even continuous, nor can you continuously trade.  (Indeed, under such assumptions the optimal investing strategy would be to sample the prices sufficiently rapidly to capture the derivatives and then to move all your assets to the stock increasing at the highest relative rate.  This crazy momentum trading would explosively destabilize the market and cause the assumptions to break.) The point of this is not to argue for or against rebalancing, but to point out that any argument for rebalancing which continues to hold under the above ideal assumptions is bogus.  (Many such arguments do.)  If a stockbroker standing to profit from commission pushes rebalancing on you with an argument that still holds under the above assumptions then he is profiting off of BS. A company CAN hold on to money.  This is called retained earnings.  Not all money is due back to the owners (i.e. stockholders), but only the amount that the board of directors chooses to pay back in the form of dividends.  There is a lot more detail around this, but this is the simple answer to your question. Cash changes hands when you buy or sell the stock. While you own the stock, you own it, not cash, so there is no cash to go anywhere. You spent your money when you bought. The seller got that money. It's gone. You hope that when you sell the stock, someone will give you more money for it than you spent. But they may give you less. Money doesn't magically appear either way, it comes from the buyer. After selling, you have the money -- however much you sold for -- and no longer have the stock. NOTE that this means the current value of a share of stock is interesting, but not really very relevant, unless you are actively buying or selling. What your portfolio is worth on paper is nothing more than an approximate snapshot at the moment you retrieve the data. It is not a promise of what will actually happen when you do sell.