Total gain of portfolio including sold stocks?
You could create your own spreadsheet of Cash Flows and use the XIRR function in Excel: The formula is:
A strategy of rebalancing assumes that the business cycle will continue, that all bull and bear markets end eventually.  Imagine that you maintained a 50% split between a US Treasury bond mutual fund (VUSTX) and an S&P 500 stock mutual fund (VFINX) beginning with a $10,000 investment in each on January 1, 2008, then on the first of each year you rebalanced your portfolio on the first of January (we can pretend the markets are open that day). The following table illustrates the values in each of those funds with the rebalancing transactions: This second table shows what that same money would look like without any rebalancing over those years: Obviously this is cherry-picking for the biggest drop we've recently experienced, but even if you skipped 2008 and 2009, the increase for a rebalanced portfolio from 2010-2017 is 85% verses 54% for the portfolio that is not being rebalanced in the same period. This is also a plenty conservative portfolio. You can see that a 100% stock portfolio dropped 40% in 2008, but the combined portfolio only dropped 18%. A 100% stock portfolio has gained 175% since 2009, compared to 105% for the balanced portfolio, but it's common to trade gains for safety as you get closer to retirement. You didn't ask about a 100% stock portfolio in your initial question. These results would be repeated in many other portfolio allocations because some asset classes outperform others one year, then underperform the next. You sell after the years it outperforms, then you buy after years that it underperforms. "Oddly enough, in the USA, there are enough cost and tax savings between buy-and-hold of a static portfolio and buying into a fund that a few brokerages have sprung up around the concept, such as FolioFN, to make it easier for small investors to manage numerous small holdings via fractional shares and no commission window trades. A static buy-and-hold portfolio of stocks can be had for a few dollars per trade.  Buying into a fund involves various annual and one time fees that are quoted as percentages of the investment.  Even 1-2% can be a lot, especially if it is every year.  Typically, a US mutual fund must send out a 1099 tax form to each investor, stating that investors share of the dividends and capital gains for each year. The true impact of this is not obvious until you get a tax bill for gains that you did not enjoy, which can happen when you buy into a fund late in the year that has realized capital gains.  What fund investors sometimes fail to appreciate is that they are taxed both on their own holding period of fund shares and the fund's capital gains distributions determined by the fund's holding period of its investments. For example, if ABC tech fund bought Google stock several years ago for $100/share, and sold it for $500/share in the same year you bought into the ABC fund, then you will receive a ""capital gains distribution"" on your 1099 that will include some dollar amount, which is considered your share of that long-term profit for tax purposes. The amount is not customized for your holding period, capital gains are distributed pro-rata among all current fund shareholders as of the ex-distribution date. Morningstar tracks this as Potential Capital Gains Exposure and so there is a way to check this possibility before investing. Funds who have unsold losers in their portfolio are also affected by these same rules, have been called ""free rides"" because those funds, if they find some winners, will have losers that they can sell simultaneously with the winners to remain tax neutral.  See ""On the Lookout for Tax Traps and Free Riders"", Morningstar, pdf In contrast, buying-and-holding a portfolio does not attract any capital gains taxes until the stocks in the portfolio are sold at a profit.  A fund often is actively managed.  That is, experts will alter the portfolio from time to time or advise the fund to buy or sell particular investments. Note however, that even the experts are required to tell you that ""past performance is no guarantee of future results.""" @BlackJack does a good answer of addressing the gains and when you are taxed on them and at what kind of rate. Money held in a brokerage account will usually be in a money-market fund, so you would own taxes on the interest it earned.   There is one important consideration that must be understood for capitol Losses.  This is called the Wash Sale Rule.  This rule comes into affect if you sell a stock at a LOSS, and buy shares of the same stock within 30 days (before or after) the sale.  A common tactic used to minimize taxes paid is to 'capture losses' when they occur, since these can be used to offset gains and lower your taxes.  This is normally done by selling a stock in which you have a LOSS, and then either buying another similar stock, or waiting and buying back the stock you sold.   However, if you are intending to buy back the same stock, you must not 'trigger' the Wash Sale Rule or you are forbidden to take the loss. Examples.  Lets presume you own 1000 shares of a stock and it's trading 25% below where you bought it, and you want to capture the loss to use on your taxes. This can be a very important consideration if trading index ETF's  if you have a loss in something like a S&P500 ETF, you would likely incur a wash sale if you sold it and bought a different S&P500 ETF from another company since they are effectively the same thing.  OTOH, if you sold an S&P500 ETF and bought something like a 'viper''total stock market' ETF it should be different enough to not trigger the wash sale rule.  If you are trying to minimize the taxes you pay on stocks, there are basically two rules to follow.  1) When a gain is involved, hold things at least a year before selling, if at all possible.  2) Capture losses when they occur and use to offset gains, but be sure not to trigger the wash sale rule when doing so. "I have heard that investing more money into an investment which has   gone down is generally a bad idea*. ""Throwing good money after bad"" so   to speak. Is investing more money into a stock, you already have a stake in,   which has gone up in price; a good idea? Other things being equal, deciding whether to buy more stocks or shares in a company you're already invested in should be made in the same way you would evaluate any investment decision and -- broadly speaking -- should not be influenced by whether an existing holding has gone up or down in value. For instance, given the current price of the stock, prevailing market conditions, and knowledge about the company, if you think there is a reasonable chance that the price will rise in the time-period you are interested in, then you may want to buy (more) stock. If you think there is a reasonable chance the price will fall, then you probably won't want to buy (more) stock. Note: it may be that the past performance of a company is factored into your decision to buy (e.g was a recent downturn merely a ""blip"", and long-term prospects remain good; or have recent steady rises exhausted the potential for growth for the time being). And while this past performance will have played a part in whether any existing holding went up or down in value, it should only be the past performance -- not whether or not you've gained or lost money -- that affects the new decision. For instance: let us suppose (for reasons that seemed valid at the time) you bought your original holding at £10/share, the price has dropped to £2/share, but you (now) believe both prices were/are ""wrong"" and that the ""true price"" should be around £5/share. If you feel there is a good chance of this being achieved then buying shares at £2, anticipating they'll rally to £5, may be sound. But you should be doing this because you think the price will rise to £5, and not because it will offset the loses in your original holding. (You may also want to take stock and evaluate why you thought it a good idea to buy at £10... if you were overly optimistic then, you should probably be asking yourself whether your current decisions (in this or any share) are ""sound""). There is one area where an existing holding does come into play: as both jamesqf and Victor rightly point out, keeping a ""balanced"" portfolio -- without putting ""all your eggs in one basket"" -- is generally sound advice. So when considering the purchase of additional stock in a company you are already invested in, remember to look at the combined total (old and new) when evaluating how the (potential) purchase will affect your overall portfolio." "You should check with your broker for details, but you can generally specify which ""lot"" you are selling.  where I've seen it, that's done by concurrently sending a ""letter of instruction"" documenting your choice of lot concurrent with the sale, but different brokers may handle this differently.  I would think this should work for the case that you describe. (In addition, the default rule used by your broker is ""probably"" first-in-first-out, which will do what you want here.) Note that this may come into play even in a margin account to the extent that you might want to specify a lot in order to obtain (or set yourself up for later benefit of) favorable tax treatment under the long-term capital gains rules" "Doesn't ""no rebalancing"" mean ""start with a portfolio and let it fly?""  Seems like incorporation of rebalancing is more sophisticated than not. Just ""buy"" your portfolio at the start and see where it ends up with no buying/selling, as compared with where it ends up if you do rebalance. Or is it not that simple?" If you mean the internal rate of return, then the quarterly rate of return which would make the net present value of these cash flows to be zero is 8.0535% (found by goal seek in Excel), or an equivalent compound annual rate of 36.3186% p.a. The net present value of the cash flows is: 10,000 + 4,000/(1+r) - 2,000/(1+r)^2 - 15,125/(1+r)^3, where r is the quarterly rate. If instead you mean Modified Dietz return, then the net gain over the period is: End value - start value - net flow = 15,125 - 10,000 - (4,000 - 2,000) = 3,125 The weighted average capital invested over the period is: 1 x 10,000 + 2/3 x 4,000 - 1/3 x 2,000 = 12,000 so the Modified Dietz return is 3,125 / 12,000 = 26.0417%, or 1.260417^(1/3)-1 = 8.0201% per quarter, or an equivalent compound annual rate of 1.260417^(4/3)-1 = 36.1504%. You are using an inappropriate formula, because we know for a fact that the flows take place at the beginning/end of the period. Instead, you should be combining the returns for the quarters (which have in fact been provided in the question). To calculate this, first calculate the growth factor over each quarter, then  link them geometrically to get the overall growth factor. Subtracting 1 gives you the overall return for the 3-quarter period. Then convert the result to a quarterly rate of return. Growth factor in 2012 Q4 is 11,000/10,000 = 1.1 Growth factor in 2013 Q1 is 15,750/15,000 = 1.05 Growth factor in 2013 Q2 is 15,125/13,750 = 1.1 Overall growth factor is 1.1 x 1.05 x 1.1 = 1.2705 Return for the whole period is 27.05% Quarterly rate of return is 1.2705^(1/3)-1 = 8.3074% Equivalent annual rate of return is 1.2705^(4/3)-1 = 37.6046% ========= I'd recommend you to refer to Wikipedia. Yes that is the case for the public company approach, but I was referring to the transaction approach:   Firm A and Firm B both have $100 in EBITDA. Firm A has $50 in cash, Firm B has $100 in cash.  Firm A sells for $500, Firm B sells for $600.  If we didn't subtract cash before calculating the multiple: Firm A: 5x Firm B: 6x  If we DO subtract cash before calculating the multiple: Firm A: 4.5x Firm B: 5x  So yea, subtracting cash does skew the multiple.