Buying and selling the same stock
Elaborating on kelsham's answer: You buy 100 shares XYZ at $1, for a total cost of $100 plus commissions. You sell 100 shares XYZ at $2, for a total income of $200 minus commissions. Exclusive of commissions, your capital gain is $100 for this trade, and you will pay taxes on that.  Even if you proceed to buy 200 shares XYZ at $1, reinvesting all your income from the sale, you still owe taxes on that $100 gain.  The IRS has met this trick before. "Unfortunately, we don't know your country, but I'd guess ""Not US"" with the hint being your use of the word bugger in a comment.  Realized profits are taxed by all tax authorities I'm aware of, i.e. the Tax Man in every country. Annually, so that you can let the profits run during the year, and offset by the losses during that year.  The exception is within a qualified retirement account. Many countries offer accounts that will let you do just what you're suggesting, start with XXX number of Quatloos in your account, trade for decades, and only take the tax hit on withdrawal. In some cases there's an opportunity to fund the account post tax, and never pay tax again. But to repeat, this is with a retirement account, not the usual trading accounts." Sorry, no, any time you sell for a profit you owe tax. If you buy for $1 and sell $1 when the price goes to $2, you would have sold only half of your initial investment. So your investment would now be worth $2 and you sell $1 leaving $1 still in the market.  This means you would have sold half your initial investment, making a profit of $0.50 on this half of your initial investment, and having to pay CGT on this amount. I think what you're asking is,  Can I buy 1000 shares of the stock at $1.  For $1000.   it goes up to $2, then sell 500 shares of the stock with proceeds of $1000, now   having my original $1000 out of it, and still owning 500 shares.    And that not create a taxable event. Since all I   did was take my cost basis back out, and didn't collect any gains.   And then I want to repeat that over and over. Nope, not in the USA anyway.   Each sale is a separate taxable event. The first sale will have proceeds of $1000 and a cost basis of $500, with $500 of capital gains, and taxes owed at the time of that sale. The remaining stock will have a cost basis of $500 and proceeds of whatever you sell it for in the future. The next batch of stock will have a cost basis of whatever you pay for it.   The only thing that works anything like the way you're thinking, is a Roth IRA...   You can put your cost basis in, pull it back out, and put it back in again, all tax free.   But every time your cost basis cycles in, that counts towed your contribution limits unless you do it fast enough to call it a rollover. No, you can not cheat the IRS. This question is also based on the assumption that the stock will return to $1 which isn't always a safe assumption and that it will continue to cycle like that repeatedly which is also likely a false assumption.
Firstly 795 is not even. Secondly - generally you would pay tax on the sale of the 122 shares, whether you buy them back or not, even one minute later, has nothing to do with it. The only reason this would not create a capital gains event is if your country (which you haven't specified) has some odd rules or laws about this that I, and most others, have never heard of before. New to investing... when I buy/sell a stock can I buy/sell at the exact market price whenever I'd like or is there more to it? Does there need to be a demand for when I'm trying to sell or am I just forcing the company to buy back my shares? Sorry if confusing/rookie question It's done by Opening Auction (http://www.advfn.com/Help/the-opening-auction-68.html): The Opening Auction Between 07.50 and   a random time between 08.00 and   08.00.30, there will be called an auction period during which time,   limit and market orders are entered   and deleted on the order book. No   order execution takes place during   this period so it is possible that the   order book will become crossed. This   means that some buy and sell orders   may be at the same price and some buy   orders may be at higher prices than   some sell orders. At the end of the random start period,   the order book is frozen temporarily   and an order matching algorithm is   run. This calculates the price at   which the maximum volume of shares in   each security can be traded. All   orders that can be executed at this   price will be filled automatically,   subject to price and priorities. No   additional orders can be added or   deleted until the auction matching   process has been completed. The opening price for each stock will   be either a 'UT' price or, in the   event that there are no transactions   resulting form the auction, then the   first 'AT' trade will be used. When there is a difference between the two ... no trading occurs. Let's look at an example: Investor A, B, C, and D all buy/sell shares of company X. Investor A wants to sell 10 shares at $20 a share (Ask price $20 x10). Investor B wants to buy 15 shares at $10 a share (Bid price $10 x15). Since the bid price and ask price are different, no sale is made. Next Investor C comes along and wants to sell 5 shares at $14 (Ask price $14 x5). Still no sale. Investor D comes along and wants to buy 5 shares for $14 each. So a sale is finally made. At this point, the stock quote moves to $14. The ask price is $20 x10 and the bid price is $10 x15. No further trading will occur until another investor is willing to buy at $20 or sell at $10.  Another discussion of this topic is shown on this post. Stock acquired through a (non-taxable) stock dividend has the same holding period as the stock on which the dividend was paid. I cannot believe noone mentioned this so far: Every decision you make is independent from previous decisions (that is, if you only care about your expected gain). This means that your decision whether to buy the option should be the same whether you bought the same option before or not. "You will almost certainly be able to sell 10,000 shares at once. The question is a matter of price. If you sell ""at market"" then you may get a lower price for each ""batch"" of the stock sold (one person buys 50, another buys 200, another buys 1000 etc) at varying prices. Will you be able to execute a single order to sell them all at the same price at the same time? Nobody can say, and it's not really a function of the company size. The exchange has what's called ""open interest"" which roughly correlates to how many people have active orders in at a given price. This number is constantly changing alongside the bid and ask (particularly for active stocks). So let's say you have 10,000 shares and you want to sell them for $100 each. What you need is at least 10,000 in open interest at $100 bid to execute. By contrast let's say you issue a limit order at $100 for 10,000 shares. Your ask will stay outstanding at that price and you'll be filled at that price if there are enough buyers. I you have a limit sell order at $100 for 10,000 shares the strike price of the stock cannot go to $100.01 until all of your sell orders are filled." Ask yourself a better question: Under my current investment criteria would I buy the stock at this price? If the answer to that question is yes you need to work out at what price you would now sell out of the position. Think of these as totally separate decisions from your original decisions to buy and at what price to sell. If you would buy the stock now if you didn't already hold a position then you should keep that position as if you had sold out at the price that you had originally seen as your take profit level and bought a new position at the current price without incurring the costs. If you would not buy now by those criteria then you should sell out as planned. This is essentially netting off two investing decisions. Something to think about is that the world has changed and if you knew what you know now then you would probably have set your price limit higher. To be disciplined as an investor also means reviewing current positions frequently and without any sympathy for past decisions. I would suggest following your quote and having a read of the web page supplied, that buys then sells or sells short then buys (the same security on the same day) four or more times in five business days, ... So it is a two way transaction that counts as 'one'. "They are not selling stocks. They are selling OJ futures contracts. Selling a futures contract at 142 gives the buyer the right to buy a fixed number of pounds of orange juice concentrate (""OJ"") on a future date at 142 cents per pound. The seller has an obligation to suppy that fixed number of pounds of OJ to the buyer on the future date for 142 cents per pound. When the seller turns around and buys future contracts at 29, the seller gets the right to buy OJ on a future date at 29. This ""zeros his position"" -- meaning he's guaranteed himself the ability to deliver the pounds of OJ he was obligated to supply when he sold futures contracts at 142. And since he'll only have to pay 29 cents per pound, and he'll be selling the OJ for 142 per pound, he'll walk away with 113 cents of profit for every pound sold. You can read a blow-by-blow account of what Winthorpe and Valentine did at the end of ""Trading Places"" here and here. Note that what they did would not be legal today under the ""Eddie Murphy rule"", which prohibits trades based on illicitly obtained government information." You are still selling one investment and buying another - the fact that they are managed by the same company should be irrelevant.  So yes, it would get the same tax treatment as if they were managed by different companies. "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." "Most of the time* you're selling to other investors, not back to the company. The stock market is a collection of bid (buy offers) and asks (sell offers). When you sell your stock as a retail investor at the ""market"" price you're essentially just meeting whatever standing bid offers are on the market.  For very liquid stocks (e.g. Apple), you can pretty much always get the displayed price because so many stocks are being traded. However during periods of very high volatility or for low-volume stocks, the quoted price may not be indicative of what you actually pay.  As an example, let's say you have 5 stocks you're trying to sell and the bid-side order book is 2 stocks for $105, 2 for $100, and 5 for $95. In this scenario the quoted price will be $105 (the best bid price), but if you accept market price you'll settle 2 for 105, 2 for 100, and 1 for 95. After your sell order goes through, the new quoted price will be $95. For high volume stocks, there will usually be so many orders near the midpoint price ($105, in this case) that you won't see any price slippage for small orders.  You can also post limit orders, which are essentially open orders waiting to be filled like in the above example. They ensure you get the price you want, but you have no way to guarantee they'll be filled or not.  Edit: as a cool example, check out the bitcoin GDAX on coinbase for a live example of what the order book looks like for stocks. You'll see that the price of bitcoin will drift towards whichever direction has the less dense order book (e.g. price drifts upwards when there are far more bids than asks.)" If you had an agreement with your friend such that you could bring back a substantially similar car, you could sell the car and return a different one to him.  The nature of shares of stock is that, within the specified class, they are the same.  It's a fungible commodity like one pound of sand or a dollar bill.  The owner doesn't care which share is returned as long as a share is returned.   I'm sure there's a paragraph in your brokerage account terms of service eluding to the possibility of your shares being included in short sale transactions. "The only general rule is ""If you would buy the stock at its current price, hold and possibly buy. If you wouldn't, sell and buy something you believe in more strongly."" Note that this rule applies no matter what the stock is doing. And that it leaves out the hard work of evaluating the stock and making those decisions. If you don't know how to do that evaluation to your own satisfaction, you probably shouldn't be buying individual stocks. Which is why I stick with index funds."