How to calculate how much a large stock position is really worth?
"This is actually a very complicated question. The key reading in this area is a seminal paper by Almgren & Chriss, ""Optimal Execution of Portfolio Transactions"" (2000). They show that there's a tradeoff between liquidating your portfolio faster and knowing the value with more certainty, versus liquidating more slowly (and likely for a higher price) but with less certainty. So for example, if you sold your entire position right now, you would know almost certainly how much you would get for the position. Or, you could sell off your position more slowly, and likely get more money, but you would have less certainty about how much you would get. The paper is available online at http://www.courant.nyu.edu/~almgren/papers/optliq.pdf" "I don't have a formula for anything like this, but it is important to note that the ""current value"" of any asset is really theoretical until you actually sell it. For example, let's consider a house.  You can get an appraisal done on your house, where your home is inspected, and the sales of similar houses in your area are compared.  However, this value is only theoretical.  If you found yourself in a situation where you absolutely had to sell your house in one week, you would most likely have to settle for much less than the appraised value. The same hold true for collectibles.  If I have something rare that I need cash for immediately, I can take it to a pawn shop and get cash.  However, if I take my time and locate a genuinely interested collector, I can get more for it. This is comparable to someone who holds a significant percentage of shares in a publicly held corporation.  If the current market value of your shares is $10 million, but you absolutely need to sell your entire stake today, you aren't going to get $10 million.  But if you take your time selling a little at a time, you are more likely to get much closer to this $10 million number. A ""motivated seller"" means that the price will drop." "One of two things is true: You own less than 5% of the total shares outstanding. Your transaction will have little to no effect on the market. For most purposes you can use the current market price to value the position. You own more than 5% of the total shares outstanding. You are probably restricted on when, where, and why you can sell the shares because you are considered part owner of the company. Regardless, how to estimate (not really ""calculate,"" since some of the inputs to the formula are assumptions a.k.a. guesses) the value depends on exactly what you plan to with the result." Something like cost = a × avg_spreadb + c × volatilityd × (order_size/avg_volume)e. Different brokers have different formulas, and different trading patterns will have different coefficients.
It's an issue of how much of a safety net you want, and part of that is going to be how much of a safety net you have in other areas. You should take into account what regular expenses you have, what emergency expenses you might have, what insurance policies you have, what deductibles those policies have, and what sources of money you have. As Alex B says, a HELOC isn't a guaranteed source of money, but it is one contingency. If you have a large amount of equity and your local real estate market is stable, your bank could cancel your HELOC, but they would have no financial incentive to do so. Other possible safety nets to consider would be friends and family, credit cards, and loans backed by retirement funds. Obviously you shouldn't rely on the last two for everyday expenses, but it's reasonable to consider them as contingencies in true emergencies.  Also, if you have a significant net worth, home equity and savings account should not be the only places you're storing your wealth. Look into stocks, bonds, and money market accounts. Your expected returns in the stock market should be higher than the interest you're paying on the HELOC. Stocks are more risky and obviously you shouldn't put all your savings there, but it is one more basket to put your eggs in, and unlike a savings account your money isn't just sitting there. If he asked you to invest his money with certain objectives which resulted in you buying specific stocks for him with his money, then sell all the stocks which you bought with his money and the capital and profits to him. You may want to calculate the trading fees that you incurred while buying these specific stocks and taxes from the sale of these stocks, withholding them to over the trading fees that you have already paid and the taxes that you might still need to pay. If you traded with his money no different than yours, then I would think of your investment account as a black box. Calculate the initial money that you both invested at the time you added his capital to the account, calculate how much it all is currently worth, then liquidate and return a percentage equal to that of his initial investment. You can account for trading fees and taxes, subtracting by the same percentage. "The mutual fund is legally its own company that you're investing in, with its own expenses. Mutual fund expense ratios are a calculated value, not a promise that you'll pay a certain percentage on a particular day. That is to say, at the end of their fiscal year, a fund will total up how much it spent on administration and divide it by the total assets under management to calculate what the expense ratio is for that year, and publish it in the annual report. But you can't just ""pay the fee"" for any given year. In a ""regular"" account, you certainly could look at what expenses were paid for each fund by multiplying the expense ratio by your investment, and use it in some way to figure out how much additional you want to contribute to ""make it whole"" again. But it makes about as much sense as trying to pay the commission for buying a single stock out of one checking account while paying for the share price out of another. It may help you in some sort of mental accounting of expenses, but since it's all your money, and the expenses are all part of what you're paying to be able to invest, it's not really doing much good since money is fungible. In a retirement account with contribution limits, it still doesn't really make sense, since any contribution from outside funds to try to pay for expense ratios would be counted as contributions like any other. Again, I guess it could somehow help you account for how much money you wanted to contribute in a year, but I'm not really sure it would help you much. Some funds or brokerages do have non-expense-ratio-based fees, and in some cases you can pay for those from outside the account. And there are a couple cases where for a retirement account this lets you keep your contributions invested while paying for fees from outside funds. This may be the kind of thing that your coworker was referring to, though it's hard to tell exactly from your description. Usually it's best just to have investments with as low fees as possible regardless, since they're one of the biggest drags on returns, and I'd be very wary of any brokerage-based fees when there are very cheap and free mutual fund brokerages out there." "Here's a link to an online calculator employing the Discounted Cash Flow method:  Discounted Cash Flows Calculator.  Description: This calculator finds the fair value   of a stock investment the   theoretically correct way, as the   present value of future earnings. You   can find company earnings via the box   below.   [...] They also provide a link to the following relevant article:  Investment Valuation: A Little Theory.  Excerpt: A company is valuable to stockholders   for the same reason that a bond is   valuable to bondholders: both are   expected to generate cash for years   into the future. Company profits are   more volatile than bond coupons, but   as an investor your task is the same   in both cases: make a reasonable   prediction about future earnings, and   then ""discount"" them by calculating   how much they are worth today. (And   then you don't buy unless you can get   a purchase price that's less than the   sum of these present values, to make   sure ownership will be worth the   headache.)   [...]" Let's suppose your friend gave your $100 and you invested all of it (plus your own money, $500) into one stock. Therefore, the total investment becomes $100 + $500 = $600. After few months, when you want to sell the stock or give back the money to your friend, check the percentage of profit/loss. So, let's assume you get 10% return on total investment of $600.  Now, you have two choices. Either you exit the stock entirely, OR you just sell his portion. If you want to exit, sell everything and go home with $600 + 10% of 600 = $660. Out of $660, give you friend his initial capital + 10% of initial capital. Therefore, your friend will get $100 + 10% of $100 = $110. If you choose the later, to sell his portion, then you'll need to work everything opposite. Take his initial capital and add 10% of initial capital to it; which is $100 + 10% of $100 = $110. Sell the stocks that would be worth equivalent to that money and that's it. Similarly, you can apply the same logic if you broke his $100 into parts. Do the maths. "Will the investment bank evaluate the worth of my company more than or less than 50 crs. Assuming the salvage value of the assets of 50 crs (meaning that's what you could sell them for to someone else), that would be the minimum value of your company (less any outstanding debts). There are many ways to calculate the ""value"" of a company, but the most common one is to look at the future potential for generating cash.   The underwriters will look at what your current cash flow projections are, and what they will be when you invest the proceeds from the public offering back into the company.  That will then be used to determine the total value of the company, and in turn the value of the portion that you are taking public. And what will be the owner’s share in the resulting public company? That's completely up to you.  You're essentially selling a part of the company in order to bring cash in, presumably to invest in assets that will generate more cash in the future.  If you want to keep complete control of the company, then you'll want to sell less than 50% of the company, otherwise you can sell as much or as little as you want." There is no formula for calculating a stock price based on the financials of a company. A stock price is set by the market and always has a component built into it that is based on something outside of the current valuation of a company using its financials. Essentially, the stock price of a company per share is whatever the best price it can get on the open market. If you are looking at how to evaluate if a stock is a good value at the current price, then look at some of the answers, but I wanted to answer this based on the way you phrased the question. "It depends on many factors, but generally, the bid/ask spread will give you an idea. There are typically two ways to buy (or sell) a security: With a limit order, you would place a buy for 100 shares at $30-. Then it's easy, in the worst case you will get your 100 shares at $30 each exactly. You may get lucky and have the price fall, then you will pay less than $30. Of course if the price immediately goes up to say $35, nobody will sell at the $30 you want, so your broker will happily sit on his hands and rake in the commission while waiting on what is now a hail Mary ask. With a market order, you have the problem you mention: The ticker says $30, but say after you buy the first 5 shares at $30 the price shoots up and the rest are $32 each - you have now paid on average $31.9 per share. This could happen because there is a limit order for 5 at $30 and 200 at $32 (you would have filled only part of that 200). You would be able to see these in the order book (sometimes shown as bid/ask spread or market depth). However, the order book is not law. Just because there's an ask for 10k shares at $35 each for your $30 X stock, doesn't mean that by the time the price comes up to $35, the offer will still be up. The guy (or algorithm) who put it up may see the price going up and decide he now wants $40 each for his 10k shares. Also, people aren't obligated to put in their order: Maybe there's a trader who intends to trade a large volume when the price hits a certain level, like a limit order, but he elected to not put in a limit order and instead watch the ticker and react in real time. Then you will see a huge order suddenly come in out of nowhere. So while the order book is informative, what you are asking is actually fundamentally impossible to know fully, unless you can read the minds of every interested trader. As others said, in ""normal"" securities (meaning traded at a major exchange, especially those in the S&P500) you simply can't move the price, the market is too deep. You would need millions of dollars to budge the price, and if you had that much money, you wouldn't be asking here on a QA site, you would have a professional financial advisor (or even a team) that specializes in distributing your large transaction over a longer time to minimize the effect on the market. With crazier stocks, such as OTC and especially worthless penny stocks with market caps of $1 mil or less, what you say is a real problem (you can end up paying multiples of the last ticker if not careful) and you do have to be careful about it. Which is why you shouldn't trade penny stocks unless you know what you're doing (and if you're asking this question here, you don't)."