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.
The upvoted answers fail to note that dividends are the only benefit that investors collectively receive from the companies they invest in. If you purchase a share for $100, and then later sell it for $150, you should note that there is always someone that purchases the same share for $150. So, you get $150 immediately, but somebody else has to pay $150 immediately. So, investors collectively did not receive any money from the transaction. (Yes, share repurchase can be used instead of dividends, but it can be considered really another form of paying dividends.) The fair value of a stock is the discounted value of all future dividends the stock pays. It is so simple! This shows why dividends are important. Somebody might argue that many successful companies like Berkshire Hathaway do not pay dividend. Yes, it is true that they don't pay dividend now but they will eventually have to start paying dividend. If they reinvest potential dividends continuously, they will run out of things to invest in after several hundred years has passed. So, even in this case the value of the stock is still the discounted value of all future dividends. The only difference is that the dividends are not paid now; the companies will start to pay the dividends later when they run out of things to invest in. It is true that in theory a stock could pay an unsustainable amount of dividend that requires financing it with debt. This is obviously not a good solution. If you see a company that pays dividend while at the same time obtaining more cash from taking more debt or from share issues, think twice whether you want to invest in such a company. What you need to do to valuate companies fairly is to estimate the amount of dividend that can sustain the expected growth rate. It is typically about 60% of the earnings, because a part of the earnings needs to be invested in future growth, but the exact figure may vary depending on the company. Furthermore, to valuate a company, you need the expected growth rate of dividends and the discount rate. You simply discount all future dividends, correcting them up by the expected dividend growth rate and correcting them down by the discount rate. "Share price is based on demand.  Assuming the same amount of shares are made available for trade then stocks with a higher demand will have a higher price.  So say a company has 1000 shares in total and that company needs to raise $100. They decide to sell 100 shares for $1 to raise their $100. If there is demand for 100 shares for at least $1 then they achieve their goal. But if the market decides the shares in this company are only worth 50 cents then the company only raises $50. So where do they get the other $50 they needed? Well one option is to sell another 100 shares. The dilution comes about because in the first scenario the company retains ownership of 900 or 90% of the equity. In the second scenario it retains ownership of only 800 shares or 80% of the equity. The benefit to the company and shareholders of a higher price is basically just math. Any multiple of shares times a higher price means there is more value to owning those shares. Therefore they can sell fewer shares to raise the same amount.  A lot of starts up offer employees shares as part of their remuneration package because cash flow is typically tight when starting a new business. So if you're trying to attract the best and brightest it's easier to offer them shares if they are worth more than those of company with a similar opportunity down the road. Share price can also act as something of a credit score. In that a higher share price ""may"" reflect a more credit worthy company and therefore ""may"" make it easier for that company to obtain credit. All else being equal, it also makes it more expensive for a competitor to take over a company the higher the share price. So it can offer some defensive and offensive advantages. All ceteris paribus of course." "In the case of Wells Fargo, I believe that free trading is linked to your overall banking relationship with the firm. So if you have a checking account with a balance of $X, or  a total relationship with the bank (""relationship"" is usually defined as loan balances + deposit balances) over a certain amount, they give you a plum like free stock trades. The theory behind this approach is that banks want to be a one-stop shop for you. The idea is that they can market the banks products to you over a period of years (lowering customer acquisition cost) and offer you a level of convenience that allows them to charge a premium for services. For example, many people will pay a rate or fee premium on a mortgage or car loan so that they can do all of their business in one place. In other cases, free trading is linked to marketing campaigns by funds. Charles Schwab started this with the ""no transaction fee"" mutual fund store many years ago -- transaction fees are actually paid for by the mutual funds who pay for placement in the program. ""Free ETF trade"" programs are similar." Sale of a stock creates a capital gain. It can be offset with losses, up to $3000 more than the gains. It can be deferred when held within a retirement account.  When you gift appreciated stock, the basis follows. So when I gifted my daughter's trust shares, there was still tax due upon sale. The kiddy tax helped reduce but not eliminate it. And there was no quotes around ownership. The money is gone, her account is for college.  No 1031 exchange exists for stock. Because the stock still has the same value as the money paid for it - you are just exchanging one asset for another (of course the stock value starts to change immediately, but for the accounting the fictional value is the buying price). For the accounting, it is similar to changing a 100$ bill in five 20$ bills - same value, still assets. 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 simple way to ask the question might be to say ""why can't I just use the same trick with my own shares to make money on the way down? Why is borrowing someone else's shares necessary to make the concept a viable one? Why isn't it just the inverse of 'going long'?"" A simple way to think about it is this: to make money by trading something, you must buy it for less than you sell it for.  This applies to stocks like anything else.  If you believe the price will go up, then you can buy them first and sell them later for a higher price.  But if you believe the price will go down, the only way to buy low and sell high is to sell first and buy later.  If you buy the stock and it goes down, any sale you make will lose you money. I'm still not sure I fully understand the point of your example, but one thing to note is that in both cases (i.e., whether you buy the share back at the end or not), you lost money.  You say that you ""made $5 on the share price dropping"", but that isn't true at all: you can see in your example that your final account balance is negative in both cases.  You paid $20 for the shares but only got $15 back; you lost $5 (or, in the other version of your example, paid $20 and got back $5 plus the depreciated shares). If you had bought the shares for $20 and sold them for, say, $25, then your account would end up with a positive $5 balance; that is what a gain would look like.  But you can't achieve that if you buy the shares for $20 and later sell them for less. At a guess, you seem to be confusing the concept of making a profit with the concept of cutting your losses.  It is true that if you buy the shares for $20 and sell them for $15, you lose only $5, whereas if you buy them for $20 and sell for $10, you lose the larger amount of $10.  But those are both losses.  Selling ""early"" as the price goes down doesn't make you any money; it just stops you from losing more money than you would if you sold later." Your question is unanswerable as you haven't provided enough information. I.e. If those shares cost $1000 and you have $50000 ( or any number above $1000) of cash available in the account then you can't possibly free ride. I think your understanding of the free ride rule is incorrect. Basically what this rule is stating is that you have to have the cash when the trade is placed in order to settle the trade. Otherwise you are taking on margin (which you can't do in a cash account). So at order entry you have to have the cash to cover the purchase so it's able to be settled. If you do, no problem and you can sell that stock before trade settlement. There is no law that says you have to hold it past trade settlement. However, you cannot spend the same dollar more than once before it settles.  This site does a good job explaining this more throughly with examples: http://www.invest-faq.com/articles/trade-day-free-ride.html Let's suppose your friend gave your $100 and you invested all of it (plus your own money, $500) into one stock. Therefore, the total investment becomes $100 + $500 = $600. After few months, when you want to sell the stock or give back the money to your friend, check the percentage of profit/loss. So, let's assume you get 10% return on total investment of $600.  Now, you have two choices. Either you exit the stock entirely, OR you just sell his portion. If you want to exit, sell everything and go home with $600 + 10% of 600 = $660. Out of $660, give you friend his initial capital + 10% of initial capital. Therefore, your friend will get $100 + 10% of $100 = $110. If you choose the later, to sell his portion, then you'll need to work everything opposite. Take his initial capital and add 10% of initial capital to it; which is $100 + 10% of $100 = $110. Sell the stocks that would be worth equivalent to that money and that's it. Similarly, you can apply the same logic if you broke his $100 into parts. Do the maths. With a short position you make your money (profit) when you buy the stocks back to close the position at a lower price than what you bought them at. As short selling is classed as speculation and not investing and you at no time own any actual assets, you cannot donate any short possition to charity. If you did want to avoid paying tax on the profits you could donate the proceeds of the profits after closing the position and thus get a tax deduction equal to the profits you made. But that raises a new and more important question, why are you trading in the first place if you are afraid to make profits in case you have to pay tax on those profits? Since I'm missing the shortest and simplest answer, I'll add it: A car also doesn't offer dividends, yet it's still worth money. A $100 bill doesn't offer dividends, yet people are willing to offer services, or goods, or other currencies, to own that $100 bill. It's the same with a stock. If other people are willing to buy it off you for a price X, it's worth at least close to price X to you. In theory the price X depends on the value of the assets of the company, including unknown values like expected future profits or losses. Speaking from experience as a trader, in practice it's very often really just price X because others pay price X. The point is that the bid and ask prices dictate what you can buy and sell at (at market, at least), and the difference between the two, or spread, contributes implicitly to your gains or losses. For example, say your $1 stock actually had a bid of $0.90 and an ask of $1.10; i.e. say that $1 was the last price. You would have to buy the stock at the ask price of $1.10, but now you can only sell that stock at the bid price of $0.90. Thus, you would need to make at least that $0.20 spread before you can make a profit. "The answer is Discounted Cash Flows. Companies that don't pay dividends are, ostensibly reinvesting their cash at returns higher than shareholders could obtain elsewhere.  They are reinvesting in productive capacity with the aim of using this greater productive capacity to generate even more cash in the future. This isn't just true for companies, but for almost any cash-generating project. With a project you can purchase some type of productive assets, you may perform some kind of transformation on the good (or not), with the intent of selling a product, service, or in fact the productive mechanism you have built, this productive mechanism is typically called a ""company"". What is the value of such a productive mechanism? Yes, it's capacity to continue producing cash into the future. Under literally any scenario, discounted cash flow is how cash flows at distinct intervals are valued.  A company that does not pay dividends now is capable of paying them in the future.  Berkshire Hathaway  does not pay a dividend currently, but it's cash flows have been reinvested over the years such that it's current cash paying capacity has multiplied many thousands of times over the decades. This is why companies that have never paid dividends trade at higher prices. Microsoft did not pay dividends for many years because the cash was better used developing the company to pay cash flows to investors in later years. A companies value is the sum of it's risk adjusted cash flows in the future, even when it has never paid shareholders a dime. If you had a piece of paper that obligated an entity (such as the government) to absolutely pay you $1,000 20 years from now, this $1,000 cash flows present value could be estimated using Discounted Cash Flow. It might be around $400, for example.  But let's say you want to trade this promise to pay before the 20 years is up.  Would it be worth anything?  Of course it would.  It would in fact typically go up in value (barring heavy inflation) until it was worth very close to $1,000 moments before it's value is redeemed. Imagine that this ""promise to pay"" is much like a non-dividend paying stock.  Throughout its life it has never paid anyone anything, but over the years it's value goes up.  It is because the discounted cash flow of the $1,000 payout can be estimated at almost anytime prior to it's payout." If the price has gone up from what it was when the person bought, he may sell to collect his profit and spend the money. If someone intends to keep his money in the market, the trick is that you don't know when the price of a given stock will peak. If you could tell the future, sure, you'd buy when the stock was at its lowest point, just before it started up, and then sell at the highest point, just before it started down. But no one knows for sure what those points are. If a stockholder really KNOWS that demand is increasing and the price WILL go up, sure, it would be foolish to sell. But you can never KNOW that. (Or if you have some way that you do know that, please call me and share your knowledge.) There's a distinction between profits and cash flow, attributed to the recognition of non-cash items.  If you have a business where your customers pay you quickly, you manage your inventory well, and you’re able to take your time in paying your suppliers, your free cash flow can be consistently positive even when your net income is not.