Calculating profits for a private fund
Thanks for the answer/comments! The time-based method was something we mooted and something I almost went with. But just to wrap this up, the method we settled on was this: Every time there is an entry or exit into the fund, we divvy out any unrealised market profits/losses according to each person's profit share (based on % of the asset purchased at buy-in) JUST BEFORE the entry/exit. These realised profits are then locked in for those particpants, and then the unrealised profits/loss counter starts at zero, we do a fresh recalculation of shareholding after the entry/exit, and then we start again. Hope this helps anyone with the same issue! The total number of shares on April 1st is 100 + 180 + 275 = 555.  The price on April 1st is required.  The current price is stated as $2, but $2 * 555 = $1110 and the current fund values is stated as $1500.  Opting to take the current value as $1500, the price on April 1st can be calculated as $1500/555 = $2.7027. The amounts invested as number of shares x share price are: (Note these investment amounts do not match the example scenario's investment amounts, presumably because the example numbers are just made up.) The monthly returns can be calculated: The current values for each investor as invested amount x returns are: Checking the total: One way I heard of, from a friend who ran a similar fund as yours, is to calculate $days of investment and divide the investment as accordingly.  For example, If I invested 10$ for 10 days and you have invested 20$ for 5 days. At the end of the 10th day my $day = 10*10=100, while your $day=20*5=100. If the investement has grown to 100$, the I should get $100/(100+100)*100=$50, you also should get the same. This I guess is equitable, you could try dividing the corpus with above method. It consideres the amount invested as well as the time invested for. I think by the above method, you could also handle the inbetween withdrawals.
"To calculate a sector (or index) P/E ratio you need to sum the market caps of the constituent stocks and divide it by the sum of the total earnings of the constituent stocks (including stocks that have negative earnings).  There are no ""per share"" figures used in the calculation. Beware when you include an individual stock that there may be multiple issues associated with the company that are not in the index.... eg. Berkshire Hathaway BRK.B is in the S&P 500 but BRK.A is not.  In contrast, Google has both GOOGL and GOOG included in the S&P 500 index but not its unlisted Class B shares.  All such shares need to be included in the market cap and figuring out the different share class ratios can be tricky." Thanks for showing me that. I can see it now. I have always used my formula, and even a senior at another company confirmed the way I calculated the returns.   Luckily, I do not work with that manager, and he has his own model, and so do I. But he was pretty cool about it when I asked about his calculations. I sell a put for a strike price at the market. The stock rises $50 over the next couple months. I've gotten the premium, but lost the rest of the potential gain, yet had the downside risk the whole time.  There's no free lunch.  Edit - you can use a BS (Black-Scholes) calculator to create your own back testing. The calculator shows a 1% interest rate, 2% yield, and 15% volatility produce a put price almost identical to the pricing I see for S&P (the SPY ETF, specifically) $205 put. No answer here, including mine, gave any reference to a study. If one exists, it will almost certainly be on an index, not individual stocks. Note that Jack's answer referencing PUTX does exactly that. The SPY ETF and it put options. My suggestion here would, in theory, let you analyze this strategy for individual stock options as well.  For SPY - With SPY at 204.40, this is the Put you'd look at -  12 times the premium is $33.36 or 16% the current price. The next part of the exercise is to see how the monthly ups and downs impact this return. A drop to $201 wipes out that month's premium.  It happens that it now March 18th, and despite a bad start to the year, we are at break-even YTD. A peek back shows In Dec you picked up $2.87 premium, (1.4% the current price then) but in Jan, it closed for a loss of $12. Ouch. Now, if you started in January, you'd have picked up 2 month's premiums and today or Monday sell the 3rd. You'd have 2.8% profit so far, vs the S&P break even.  Last, for now, when selling a naked put, you have to put up margin money. Not sure how much, but I use percent of the value of underlying stock to calculate returns. That choice is debatable, it just keeps percents clean. Else you put up no money and have infinite return. "When we talk about compounding, we usually think about interest payments. If you have a deposit in a savings account that is earning compound interest, then each time an interest payment is made to your account, your deposit gets larger, and the amount of your next interest payment is larger than the last. There are compound interest formulas that you can use to calculate your future earnings using the interest rate and the compounding interval.  However, your mutual fund is not earning interest, so you have to think of it differently. When you own a stock (and your mutual fund is simply a collection of stocks), the value of the stock (hopefully) grows. Let's say, for example, that you have $1000 invested, and the value goes up 10% the first year. The total value of your investment has increased by $100, and your total investment is worth $1100. If it grows by another 10% the following year, your investment is then $1210, having gained $110.  In this way, your investment grows in a similar way to compound interest. As your investment pays off, it causes the value of the investment to grow, allowing for even higher earnings in the future. So in that sense, it is compounding. However, because it is not earning a fixed, predictable amount of interest as a savings account would, you can't use the compound interest formula to calculate precisely how much you will have in the future, as there is no fixed compounding interval.  If you want to use the formula to estimate how much you might have in the future, you have to make an assumption on the growth of your investment, and that growth assumption will have a time period associated with it. For example, you might assume a growth rate of 10% per year. Or you might assume a growth rate of 1% per month. This is what you could use in a compound interest formula for your mutual fund investment.  By reinvesting your dividends and capital gains (and not taking them out in cash), you are maximizing your ""compounding"" by allowing those earnings to cause your investment to grow." Part A solution:  Assume no turnover in A.:      Average Balance * Annual Interest - Average Balance * Annual Cost of funds + Annual Fee = Profit from A        Profit From A = Average Balance * Interest Rate - Cost of Funds * Average Balance + Annual Fee     So for B here is the sneaky thing, the Average Balance is 1/12 of the Volume... That makes it really simple...       Volume * InterChange - Average Balance * Cost of Funds + Annual Fee = Profit From A       Volume = 12 x Average Balance So:       12 x Average Balance * Interchange (0.015) - Average Balance * Cost of Funds (0.04) + Annual Fee (Say 50)= Profit From A (260)       0.18* Average Balance - 0.04 * Average Balance = 210  Average Balance = 210/.14  Annual turnover = 12* Average Balance   Come @ me bro :p This is a note from my broker, CMC Markets, who use Morningstar: Morningstar calculate the P/E Ratio using a weighted average of the most recent earnings and the projected earnings for the next year. This may result in a different P/E Ratio to those based solely on past earnings as reported on some sites and other publications. They show the P/E as being 9.93. So obviously past earnings would usually be used but you would need to check with your source which numbers they are using. Also, as BHP's results just came out yesterday it may take a while for the most recent financial details to be updated. "Hello! I am working on a project where I am trying to determine the profit made by a vendor if they hold our funds for 5 days in order to collect the interest on those funds during that period before paying a third party.  Currently I am doing ""Amount x(Fed Funds Rate/365)x5"" but my output seems too low. Any advice?" 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. The fund should be reporting returns net of expenses, so your interpretation is right; it made something like 0.42% (which sounds plausible, based on current yields on short-term securities), and the 0.05% is what's left after expenses. I've never seen a regular mutual fund report raw returns before expenses.  If one does, the my personal opinion would be that they're trying to snooker you, as that number isn't actually representative of anybody's actual returns.   If you look carefully, you should be able to find a table that reports several kinds of adjusted returns for the fund: As to what happens if a fund can't earn enough returns to cover its expenses, in that case the value of the fund shares will decrease.  This happens from time to time with riskier funds.  It shouldn't happen with a money market fund because both the returns and the expenses are fairly predictable, so the fund managers should be able to avoid it, unless they get caught up in a major crisis like the 2008 banking crisis.  In ordinary times, a money market fund managers who couldn't keep expenses below income would find themselves looking for a new job fairly quickly. Finally, for what it's worth, 0.37% is a really high expense ratio for a money market fund.  If you were to shop around, you could easily find comparable funds with expenses less than half that. Some personal finance packages can track basis cost of individual purchase lots or fractions thereof. I believe Quicken does, for example. And the mutual funds I'm invested in tell me this when I redeem shares. I can't vouch for who/what would make this visible at times other than sale; I've never had that need. For that matter I'm not sure what value the info would have unless you're going to try to explicitly sell specific lots rather than doing FIFO or Average accounting. "Generally if you are using FIFO (first in, first out) accounting, you will need to match the transactions based on the number of shares. In your example, at the beginning of day 6, you had two lots of shares, 100 @ 50 and 10 @ 52.  On that day you sold 50 shares, and using FIFO, you sold 50 shares of the first lot.  This leaves you with 50 @ 50 and 10 @ 52, and a taxable capital gain on the 50 shares you sold. Note that commissions incurred buying the shares increase your basis, and commissions incurred selling the shares decrease your proceeds.  So if you spent $10 per trade, your basis on the 100 @ 50 lot was $5010, and the proceeds on your 50 @ 60 sale were $2990.  In this example you sold half of the lot, so your basis for the sale was half of $5010 or $2505, so your capital gain is $2990 - 2505 = $485. The sales you describe are also ""wash sales"", in that you sold stock and bought back an equivalent stock within 30 days.  Generally this is only relevant if one of the sales was at a loss but you will need to account for this in your code.  You can look up the definition of wash sale, it starts to get complex. If you are writing code to handle this in any generic situation you will also have to handle stock splits, spin-offs, mergers, etc. which change the number of shares you own and their cost basis.  I have implemented this myself and I have written about 25-30 custom routines, one for each kind of transaction that I've encountered.  The structure of these deals is limited only by the imagination of investment bankers so I think it is impossible to write a single generic algorithm that handles them all, instead I have a framework that I update each quarter as new transactions occur." The Finance functions in spreadsheet software will calculate this for you.  The basic functions are for Rate, Payment, PV (present value), FV (Future value), and NPER, the number of periods.  The single calculation faces a couple issues, dealing with inflation, and with a changing deposit. If you plan to save for 30 years, and today are saving $500/mo, for example, in ten years I hope the deposits have risen as well. I suggest you use a spreadsheet, a full sheet, to let you adjust for this.  Last, there's a strange effect that happens. Precision without accuracy. See the results for 30-40 years of compounding today's deposit given a return of 6%, 7%, up to 10% or so. Your forecast will be as weak as the variable with the greatest range. And there's more than one, return, inflation, percent you'll increase deposits, all unknown, and really unknowable.  The best advice I can offer is to save till it hurts, plan for the return to be at the lower end of the range, and every so often, re-evaluate where you stand. Better to turn 40, and see you are on track to retire early, than to plan on too high a return, and at 60 realize you missed it, badly.  As far as the spreadsheet goes, this is for the Google Sheets -  Type this into a cell =nper(0.01,-100,0,1000,0) It represents 1% interest per month, a payment (deposit) of $100, a starting value of $0, a goal of $1000, and interest added at month end. For whatever reason, a starting balance must be entered as a negative number, for example - =nper(0.01,-100,-500,1000,0) Will return 4.675, the number of months to get you from $500 to $1000 with a $100/mo deposit and 1%/mo return. Someone smarter than I (Chris Degnen comes to mind) can explain why the starting balance needs to be entered this way. But it does show the correct result. As confirmed by my TI BA-35 financial calculator, which doesn't need $500 to be negative. Also, from personal experience, most banks' internal IT systems are bare minimum to keep working. Outside of trading systems the back office are often on Lotus Notes 99 or similar just because back office is seen as a cost and it's easy to justify not upgrading IT systems.  For sure, if the ROI is right it might get approved but it's hard to overstate how much time of your average back office employee is already spent fighting shitty systems that could be improved with today's tech. Your actual question has nothing to do with the technical issue of linking a PayPal account to a bank account. It is all about the accounting of the money. That is, what you claim as income and what you can prove to the taxman. Yes, you will need to separate the money. Linking to a business account is probably the way to go. From there, it is about how you keep track of the money and account for it.  How you do the accounting is a different question. So: No, it does not automatically become business income just because it goes into a business bank account. You still have to keep track of said income and claim it somewhere on some tax form(s). The point of the separate business account is to avoid the commingling of the the money which may lead to you losing the liability protection of an incorporation. The bank doesn't file your taxes for you.