Selling a stock for gain to offset other stock loss
Long term gains are taxed at 15% maximum.  Losses, up to the $3K/yr you cited, can offset ordinary income, so 25% or higher, depending on your income. Better to take the loss that way. With my usual disclaimer: Do not let the tax tail wag the investing dog.
When you sell a stock that you own, you realize gains, or losses. Short-term gains, realized within a year of buying and selling an asset, are taxed at your maximum (or marginal) tax rate. Long term-gains, realized after a year, are taxed at a lower, preferential rate. The first thing to consider is losses. Losses can be cancelled against gains, reducing your tax liability. Losses can also be carried over to the next tax year and be redeemed against those gains. When you own a bunch of the same type of stock, bought at different times and prices, you can choose which shares to sell. This allows you to decide whether you realize short- or long-term gains (or losses). This is known as lot matching (or order matching). You want to sell the shares that lost value before selling the ones that gained value. Booking losses reduces your taxes; booking gains increases them. If faced with a choice between booking short term and long term losses, I'd go with the former. Since net short-term gains are taxed at a higher rate, I'd want to minimize the short-term tax liability before moving on to long-term tax liability. If my remaining shares had gains, I'd sell the ones purchased earliest since long-term gains are taxed at a lower rate, and delaying the booking of gains converts short-term gains into long-term ones. If there's a formula for this, I'd say it's  (profit - loss) x (tax bracket) = tax paid The loss for B can be used to write off the gain for A.  You will fill out a schedule 3 with cost base and proceeds of disposition.  This will give you a $0 capital gain for the year and an amount of $5 (50% of the $10 loss) you can carry forward to offset future capital gains.  You can also file a T1-a and carry the losses back up to 3 years if you're so inclined.  It can't be used to offset other income (unless you die). Your C and D trades can't be on income account except for very unusual circumstances.  It's not generally acceptable to the CRA for you to use 2 separate accounting methods.  There are some intricacies but you should probably just use capital gains.   There is one caveat that if you do short sales of Canadian listed securities, they will be on income account unless you fill out form T-123 and elect to have them all treated as capital gains. I just remembered one wrinkle in carrying forward capital losses.  They don't reduce your capital gains anymore, but they reduce your taxable income.  This means your net income won't be reduced and any benefits that are calculated from that (line 236), will not get an increase. Your three options are: Options 2 and 3 are obviously identical (other than transaction costs), so if you want to keep the stock, go for option 1, otherwise, go for option 3 since you have the same effect as option 2 with no transaction costs.  The loss will likely also offset some of the other short term gains you mentioned. "Your strategy fails to control risk. Your ""inversed crash"" is called a rally. And These kind of things often turn into bigger rallies because of short squeezes, when all the people that are shorting a stock are forced to close their stock because of margin calls - its not that shorts ""scramble"" to close their position, the broker AUTOMATICALLY closes your short positions with market orders and you are stuck with the loss. So no, your ""trick"" is not enough. There are better ways to profit from a bearish outlook." You need to use one of each, so a single order wouldn't cover this:  The stop-loss order could be placed to handle triggering a sell market order if the stock trades at $95 or lower.  If you want, you could use a stop-limit order if you have an exit price in mind should the stock price drop to $95 though that requires setting a price for the stop to execute and then another price for the sell order to execute. The limit sell order could be placed to handle triggering a sell if the stock rises above $105. On the bright side, once either is done the other could be canceled as it isn't applicable anymore. In a comment on this answer you asked  It's not clear to me why the ability to defer the gains would matter (since you never materially benefit until you actually sell) but the estate step up in basis is a great point! Could you describe a hypothetical exploitive scenario (utilizing a wash sale) in a little more detail?  This sounds like you still have the same question as originally, so I'll take a stab at answering with an example.   I sell some security for a $10,000 profit.  I then sell another security at a $10,000 loss and immediately rebuy.  So pay no taxes (without the rule).  Assuming a 15% rate, that's $1500 in savings which I realize immediately.  Next year, I sell that same security for a $20,000 profit over the $10,000 loss basis (so a $10,000 profit over my original purchase).  I sell and buy another security to pay no taxes.  In fact, I pay no taxes like this for fifty years as I live off my investments (and a pension or social security that uses up my tax deductions).  Then I die.  All my securities step up in basis to their current market value.  So I completely evade taxes on $500,000 in profits.  That's $75,000 in tax savings to make my heirs richer.  And they're already getting at least $500,000 worth of securities.   Especially consider the case where I sell a privately held security to a private buyer who then sells me back the same shares at the same price.   Don't think that $10,000 is enough?  Remember that you also get the original value.  But this also scales.  It could be $100,000 in gains as well, for $750,000 in tax savings over the fifty years.  That's at least $5 million of securities.   The effective result of this would be to make a 0% tax on capital gains for many rich people.   Worse, a poorer person can't do the same thing.  You need to have many investments to take advantage of this.  If a relatively poor person with two $500 investments tried this, that person would lose all the benefit in trading fees.  And of course such a person would run out of investments quickly.   Really poor people have $0 in investments, so this is totally impractical. "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." "You have to calculate the total value of all shares and then ask yourself ""Would I invest that amount of money in this stock?""  If the answer is yes, then only sell what you need to sell. Take the $3k loss against your income, if you have no other gains.   If you would not invest that amount of cash in that stock, then sell it all right now and carry forward the excess loss every year. Note at any point you have capital gains you can offset all of them with your loss carryover (not just $3k)." "This is called a Contingent Order and is set up so if one order is filled (in this case) the other order is cancelled.  It's a common desire that one would wish to have a stop-loss in place but also a targeted sell price for their in-the-money sell point.  Your broker will tell you all you need to know about how to enter this, if you explain you'd like to place a contingent order. (As Victor noted below, your specific order would be a ""One Cancels Other"" or ""OCO"") Great first question, welcome to Money,SE." As I recall, the gain for ISOs is considered ordinary income, and capital losses can only negate up to $3000 of this each year.  If you exercised and held the stock, you have ordinary income to the exercise price, and cap gain above that, if you hold the stock for two years.  EDIT - as noted below, this answer works for USians who found this question, but not for the OP who is Canadian, or at least asked a question at it relates to Canada's tax code. If one wants to have a bound on the loss percentages that are acceptable, this is would be a way to enforce that. For example, suppose someone wants to have a 5% stop-loss but doesn't want this to be worse than 10% as if the stock goes down more than 10% then the sell shouldn't happen. Thus, if the stock opened in a gap down 15% one day, this triggers the stop-loss and would exit at too low of a price as the gap was quite high as I wonder how familiar are you with how much a stock's price could change that makes the prices not be as continuous as one would think. At least this would be my thinking on a volatile stock where one may want to try to limit losses if the stock does fall within a specific range. Purchases and sales from the same trade date will both settle on the same settlement date. They don't have to pay for their purchases until later either. Because HFT typically make many offsetting trades -- buying, selling, buying, selling, buying, selling, etc -- when the purchases and sales settle, the amount they pay for their purchases will roughly cancel with the amount they receive for their sales (the difference being their profit or loss). Margin accounts and just having extra cash around can increase their ability to have trades that do not perfectly offset. In practice, the HFT's broker will take a smaller amount of cash (e.g. $1 million) as a deposit of capital, and will then allow the HFT to trade a larger amount of stock value long or short (e.g. $10 million, for 10:1 leverage). That $1 million needs to be enough to cover the net profit/loss when the trades settle, and the broker will monitor this to ensure that deposit will be enough. Equal sized gains and losses in alternating years would lead to an   unjust positive tax. On the contrary. If I can take my gains at the long term rate (15%) in even years, but take losses in odd years, up to $3000, or let them offset short term gains at ordinary rate, I've just gamed the system.  What is the purpose of the wash sale rule? Respectfully, we here can do a fine job of explaining how a bit of tax code works. And we can suggest the implication of those code bits. But, I suspect that it's not easy to explain the history of particular rules. For wash sale, the simple intent is to not let someone take a loss without actually selling the stock for a time. You'd be right to say the +/- 30 days is arbitrary.  I'd ask you to keep 2 things in mind if you continue to frequent this board - When you buy a stock, you become a partial owner of the company that the stock is for. As the company is valued at a higher or lower amount, the stock will reflect that by gaining or losing value. You still own that stock. For example, if you bought a stock for $10 per share and next week it is worth $8 dollars per share, the only loss incurred is on paper. You do not have to pay the difference (which I think is what you are asking?) and will only physically lose that money if you sell at that point. Similarly if that stock becomes worth $12, you have only gained money on paper and can only physically see it if you sell at that point. It depends to some extent on how you interpret the situation, so I think this is the general idea. Say you purchase one share at $50, and soon after, the price moves up, say, to $55. You now have an unrealized profit of $5. Now, you can either sell and realize that profit, or hold on to the position, expecting a further price appreciation. In either case, you will consider the price change from this traded price, which is $55, and not the price you actually bought at. Hence, if the price fell to $52 in the next trade, you have a loss of $3 on your previous profit of $5. This (even though your net P&L is calculated from the initial purchase price of $50), allows you to think in terms of your positions at the latest known prices. This is similar to a Markov process, in the sense that it doesn't matter which route the stock price (and your position's P&L) took to get to the current point; your decision should be based on the current/latest price level.