how do capital gains work if you don't know the original purchase price?
"There are two scenarios to determine the relevant date, and then a couple of options to determine the relevant price. If the stocks were purchased in your name from the start - then the relevant date is the date of the purchase. If the stocks were willed to you (i.e.: you inherited them), then the relevant date is the date at which the person who willed them to you had died. You can check with the company if they have records of the original purchase. If it was in ""street name"" - they may not have such records, and then you need to figure out what broker it was to hold them. Once you  figured out the relevant date, contact the company's ""investor relationships"" contact and ask them for the adjusted stock price on that date (adjusted for splits/mergers/acquisitions/whatever). That would be the cost basis per share you would be using. Alternatively you can research historical prices on your favorite financial information site (Google/Yahoo/Bloomberg or the stock exchange where the company is listed). If you cannot figure the cost basis, or it costs too much - you can just write cost basis as $0, and claim the whole proceeds as gains. You'll pay capital gains tax on the whole amount, but that may end up being cheaper than conducting the investigation to reveal the actual numbers."
"It would be useful to forget about the initial price that you invested - that loss happened, it's over and irreversible, it's a sunk cost; and anchoring on it would only cause you to make worse decisions. Getting ""back"" from a loss is done exactly the same as growing an investment that didn't have such a loss. You have x units of stock that's currently priced $46.5 - that is your blank slate; you need to decide wether you should hold that stock (i.e., if $46.5 is undervalued and likely to increase) or it's likely to fall further and you should sell it.   The decision you make should be exactly the same as if you'd bought it a bit earlier for $40." "I think it's easiest to illustrate it with an example... if you've already read any of the definitions out there, then you know what it means, but just don't understand what it means.  So, we have an ice cream shop. We started it as partners, and now you and I each own 50% of the company. It's doing so well that we decide to take it public.  That means that we will be giving up some of our ownership in return for a chance to own a smaller portion of a bigger thing. With the money that we raise from selling stocks, we're going to open up two more stores.  So, without getting into too much of the nitty gritty accounting that would turn this into a valuation question, let's say we are going to put 30% of the company up for sale with these stocks, leaving you and me with 35% each. We file with the SEC saying we're splitting up the company ownership with 100,000 shares, and so you and I each have 35,000 shares and we sell 30,000 to investors.  Then, and this depends on the state in the US where you're registering your publicly traded corporation, those shares must be assigned a par value that a shareholder can redeem the shares at. Many corporations will use $1 or 10 cents or something nominal.  And we go and find investors who will actually pay us $5 per share for our ice cream shop business. We receive $150,000 in new capital. But when we record that in our accounting, $5 in total capital per share was contributed by investors to the business and is recorded as shareholder's equity. $1 per share (totalling $30,000) goes towards actual shares outstanding, and $4 per share (totalling $120,000) goes towards capital surplus.  These amounts will not change unless we issue new stocks. The share prices on the open market can fluctuate, but we rarely would adjust these. Edit: I couldn't see the table before. DumbCoder has already pointed out the equation Capital Surplus = [(Stock Par Value) + (Premium Per Share)] * (Number of Shares) Based on my example, it's easy to deduce what happened in the case you've given in the table. In 2009 your company XYZ had outstanding Common Stock issued for $4,652. That's probably (a) in thousands, and (b) at a par value of $1 per share. On those assumptions we can say that the company has 4,652,000 shares outstanding for Year End 2009.  Then, if we guess that's the outstanding shares, we can also calculate the implicit average premium per share: 90,946,000 ÷ 4,652,000 == $19.52. Note that this is the average premium per share, because we don't know when the different stocks were issued at, and it may be that the premiums that investors paid were different. Frankly, we don't care.  So clearly since ""Common Stock"" in 2010 is up to $9,303 it means that the company released more stock. Someone else can chime in on whether that means it was specifically a stock split or some other mechanism... it doesn't matter. For understanding this you just need to know that the company put more stock into the marketplace... 9,303 - 4,652 == 4,651(,000) more shares to be exact. With the mechanics of rounding to the thousands, I would guess this was a stock split.  Now. What you can also see is that the Capital Surplus also increased. 232,801 - 90,946 == 141,855. The 4,651,000 shares were issued into the market at an average premium of 141,855 ÷ 4,651 == $30.50. So investors probably paid (or were given by the company) an average of $31.50 at this split.  Then, in 2011 the company had another small adjustment to its shares outstanding. (The Common Stock went up). And there was a corresponding increase in its Capital Surplus.  Without details around the actual stock volumes, it's hard to get more exact. You're also only giving us a portion of the Balance Sheet for your company, so it's hard to go into too much more detail. Hopefully this answers your question though." When property changes hands the sale prices may or may not be used to determine the appraised value of the property, and they may or may not be used to determine the appraised value of other properties. Because of the nature of the transaction: you already have an existing business relationship, the local government is likely to ignore the data point provided by your transaction when determining values of similar properties. They have no idea if there was some other factor used to determine the price. They will also not include in the calculation transactions that are a result of foreclosure becasue the target price is the loan value not the true value.  California and some other jurisdictions do add another wrinkle. You will need to determine if the transaction will trigger a reevaluation of the property value. In some states the existing laws of the state limited the annual growth of the assessment, but that could now be recaptured if the jurisdiction rules that this is a new ownership: California Board of Equalization - Change in Ownership - Frequently Asked Questions How does a change in ownership affect property taxes? Each county assessor's office reviews all recorded deeds for that   county to determine which properties require reappraisal under the   law. The county assessors may also discover changes in ownership   through other means, such as taxpayer self-reporting, field   inspections, review of building permits and newspapers. Once the   county assessor has determined that a change in ownership has   occurred, Proposition 13 requires the county assessor to reassess the   property to its current fair market value as of the date ownership   changed. Since property taxes are based on the assessed value of a property at   the time of acquisition, a current market value that is higher than   the previously assessed Proposition 13 adjusted base year value will   increase the property taxes. Conversely, if the current market value   is lower than the previously assessed Proposition 13 adjusted base   year value, then the property taxes on that property will decrease. Only that portion of the property that changes ownership, however, is   subject to reappraisal. For example, if 50 percent of the property is   transferred, the assessor will reassess only 50 percent of the   property at its current fair market value as of the date of the   transfer, and deduct 50 percent from any existing Proposition 13 base   year value. In most cases, when a person buys a residence, the entire   property undergoes a change in ownership and 100 percent of the   property is reassessed to its current market value. Simple, there is no magic price adjustment after sales - why do you expect the stock price to change? The listed price of a stock is what someone was willing to pay for it in the last deal that was concluded. If any amount of stock changes ownership, this might have the effect that other people are willing to buy it for a higher price - or not. It is solely in the next buyer's decision what he is willing to pay. Example: if you think Apple stocks are worth 500$ a piece, and I buy a million of them, you might still think they are worth 500$. Or you might see this as a reason that they are worth 505$ now. If you were a business, all your assets would have a dollar value, so when you sold them you'd decrease the amount of assets by that amount and increase in cash, and if there was a profit on the sale it would go in as income, if there was loss it would count as a cost (or a loss)... so if there was a profit it would increase Equity, a loss then it would decrease Equity.  Since it's not really worthwhile doing a estimated cost for everything that you have, I'd just report it as income like you are doing and let the amount of equity increase proportionately. So, implicitly you always had roughly that amount of equity, but some of it was in the form of assets, and now you're liquidating those assets so the amount shows up in GnuCash. When you buy new things you might sell later, you could consider adding them as assets to keep track of this explicitly (but even then you have problems-- the price of things changes with time and you might not want to keep up with those price changes, it's a lot of extra work for a family budget) -- for stuff you already have it's better to treat things as you are doing and just treat the money as income-- it's easier and doesn't really change anything-- you always had that in equity, some of it was just off the books and now you are bringing it into the books. "There is one other factor that I haven't seen mentioned here.  It's easy to assume that if you buy a stock, then someone else (another stock owner) must have sold it to you.  This is not true however, because there are people called ""market makers"" whose basic job is to always be available to buy shares from those who wish to sell, and sell shares to those who wish to buy.  They could be selling you shares they just bought from someone else, but they also could simply be issuing shares from the company itself, that have never been bought before. This is a super oversimplified explanation, but hopefully it illustrates my point." When I invest in a business valued at $50,000, I pay $25,000 and receive 50% equity. Does that $25,000 go to the current owner of the business, or into the capital of the business itself?  Who receives the money depends on who is selling you the equity.  There are a couple of different scenarios that can fit your question. You could buy existing shares from the current owner(s) of the company.  In this case, the current owner(s) would be receiving the funds from you, and in return giving you their stake in the company.  So if you all agree that the value of the business is $50,000, and you give $25,000 to the current owner(s), they give you half of their shares.  The value of the company has not changed. The company could be issuing new shares.  This is called stock dilution, or an increase in authorized share capital.  Let's say that everyone agrees that the value of the business is $50,000.  The company could create new shares and sell them to you for $25,000.  In this case, the value of the company has jumped to $75,000; you now control one-third of the company, and the existing owner(s), who previously owned 100% of the company, now only own two-thirds.  In order for you to end up with 50% of the company in this case, you would have to invest $50,000 instead, which would result in the company being valued at $100,000.   If you are wondering why the current owners would agree to this second scenario, there are two questions that address this: Note that the rules around wash sales vary depending on where you live. For the U.S., the wash sale rules say that you cannot buy a substantially identical stock or security within 30 days (before or after) your sale. So, you could sell your stock today to lock in the capital losses. However, you would then have to wait at least 30 days before purchasing it back. If you bought it back within 30 days, you would disqualify the capital loss event. The risk, of course, is that the stock's price goes up substantially while you are waiting for the wash sale period. It's up to you to determine if the risk outweighs the benefit of locking in your capital losses. Note that this applies regardless of whether you sell SOME or ALL of the stock. Or indeed, if we are talking about securities other than stocks. "I'm going to ignore your numbers to avoid spending the time to understand them.  I'm just going to go over the basic moving parts of trading an upside down car against another financed car because I think you're conflating price and value.  I'm also going to ignore taxes, and fees, and depreciation. The car has an acquisition cost (price) then it has a value.  You pay the price to obtain this thing, then in the future it is worth what someone else will pay you. When you finance a car you agree to your $10,000 price, then you call up Mr. Bank and agree to pay 10% per year for 5 years on that $10,000.  Mr. Banker wires over $10,000 and you drive home in your car.   Say in a year you want a different car.  This new car has a price of $20,000, and wouldn't you know it they'll even buy your current car from you.  They'll give you $7,000 to trade in your current car. Your current car has a value of $7,000.  You've made 12 payments of $188.71.  Of those payments about $460 was interest, you now owe about $8,195 to Mr. Banker. The new dealership needs to send payment to Mr. Banker to get the title for your current car.  They'll send the $7,000 they agreed to pay for your car.  Then they'll loan you the additional $1,195 ($8,195 owed on the car minus $7,000 trade in value).   Your loan on the new car will be for $21,195, $20,000 for the new car and $1,195 for the amount you still owed on the old car after the dealership paid you $7,000 for your old car. It doesn't matter what your down-payment was on the old car, it doesn't matter what your payment was before, it doesn't matter what you bought your old car for.  All that matters is how much you owe on it today and how much the buyer (the dealership) is willing to pay you for it. How much of this is ""loss"" is an extremely vague number to derive primarily because your utility of the car has a value.  But it could be argued that the $1,195 added on to your new car loan to pay for the old car is lost." 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. "To a certain degree ""the only sure thing I know is the price I paid for the stock is the fair price at the time I buy it"" is absolutely right, by definition, and by the law of the free and efficient market and forces of supply and demand, freedom of public information about share price sensitive information, etc, etc, etc, and you've made a good point that eludes many investors I'd say. However, in practise, the market has many participants, and they will all be arriving at a different idea of what the ""fair price"" is by way of a slightly different analysis and slightly different information. In theory they all have the same information, but unfortunately in practise there is always some disparity. When one participant feels a stock is undervalued though the last thing they want to do is say so, instead they will start buying stock. They might feel it is undervalued by 20%, but that doesn't mean they'll keep buying and buying until it gets to 20%, they might push the price up just a little, then let the price drift down again, buy some more, relax, buy some more, etc. Over time the price will rise of course because the supply will become weaker, but even if the participant is correct about the 20% the price might have only risen 7% by the time they acquire all the stock they want given their risk models, market exposure and margin guidelines, etc, and it might be more than a year later before the price has actually risen to 20%, presumably because more and more other market participants have come to the same conclusion. The opposite can obviously also happen, a participant might dump stock it feels is over valued long before it hits the values it believes in. So right away you can see that pricing might not really reflect value, or ""fair price""." You realise a capital gain as soon as you sell the stock. At that point, you will have to pay taxes on the profits when you fill in your tax return. The fact that you used the money to subsequently purchase other stocks is not relevant, unless you sell those stocks within the same tax year. For example, purchase $5000 of stock A in 2010. Sell for $6000 in 2010. Purchase $6000 of stock B in 2010. Sell stock B for $6500 in 2010. Purchase $6500 of stock C in 2010. Sell stock C for $7000 in 2011. You owe capital gains on ($6000 - $5000) + ($6500 - $6000) = $1500 for tax year 2010. You owe capital gains on ($7000 - $6500) = $500 for 2011. I think the answer you are looking for is:  You are not taxed on the original basis (purchase cost) of your investment.  If you pay $30 a share, and sell at $35, the $5 per share gain is taxable at time of sale.  But the $30 basis cost doesn't enter into tax calculations at all.  (So it's important to keep good records on your investments and how much you paid for them at purchase.) "To add to @keshlam's answer slightly a stock's price is made up of several components: the only one of these that is known even remotely accurately at any time is the book value on the day that the accounts are prepared. Even  completed cashflows after the books have been prepared contain some slight unknowns as they may be reversed if stock is returned, for example, or reduced by unforeseen costs.  Future cashflows are based on (amongst other things) how many sales you expect to make in the future for all time. Exercise for the reader: how many iPhone 22s will apple sell in 2029? Even known future cashflows have some risk attached to them; customers may not pay for goods, a supplier may go into liquidation and so need to change its invoicing strategy etc.. Estimating the risk on future cashflows is highly subjective and depends greatly on what the analyst expects the exact economic state of the world will be in the future. Investors have the choice of investing in a risk free instrument (this is usually taken as being modelled by the 10 year US treasury bond) that is guaranteed to give them a return. To invest in anything riskier than the risk free instrument they must be paid a premium over the risk free return that they would get from that. The risk premium is related to how likely they think it is that they will not receive a return higher than that rate. Calculation of that premium is highly subjective; if I know the management of the company well I will be inclined to think that the investment is far less risky (or perhaps riskier...) than someone who does not, for example. Since none of the factors that go into a share price are accurately measurable and many are subjective there is no ""right"" share price at any time, let alone at time of IPO. Each investor will estimate these values differently and so value the shares differently and their trading, based on their ever changing estimates, will move the share price to an indeterminable level. In comments to @keshlam's answer you ask if there is enough information to work out the share price if a company buys out the company before IPO. Dividing the price that this other company paid by the relative ownership structure of the firm would give you an idea of what that company thought that the company was worth at that moment in time and can be used as a surrogate for market price but it will not and cannot accurately represent the market price as other investors will value the firm differently by estimating the criteria above differently and so will move the share price based on their valuation." "I like this explanation the best.  EV is trying to get at the value of the underlying business, excluding the capital structure you currently have on the company.  If your lemonade stand is worth $100, but the business also comes with $50 in cash lying around (and no debt), then the EV is $100.  But the price you'd pay the owner (the ""market cap"") is $150, because it's like you get an immediate cash rebate."